[i]20 problems for 25 minutes.[/i]


[b]p1.[/b] What is $2018 - 3018 + 4018$?


[b]p2.[/b] What is the smallest integer greater than $100$ that is a multiple of both $6$ and $8$?


[b]p3.[/b] What positive real number can be expressed as both $\frac{b}{a}$ and $a:b$ in base $10$ for nonzero digits $a$ and $b$? Express your answer as a decimal.


[b]p4.[/b] A non-degenerate triangle has sides of lengths $1$, $2$, and $\sqrt{n}$, where $n$ is a positive integer. How many possible values of $n$ are there?


[b]p5.[/b] When three integers are added in pairs, and the results are $20$, $18$, and $x$. If all three integers sum to $31$, what is $x$?


[b]p6.[/b] A cube's volume in cubic inches is numerically equal to the sum of the lengths of all its edges, in inches. Find the surface area of the cube, in square inches.


[b]p7.[/b] A $12$ hour digital clock currently displays$ 9 : 30$. Ignoring the colon, how many times in the next hour will the clock display a palindrome (a number that reads the same forwards and backwards)?


[b]p8.[/b] SeaBay, an online grocery store, offers two different types of egg cartons. Small egg cartons contain $12$ eggs and cost $3$ dollars, and large egg cartons contain $18$ eggs and cost $4$ dollars. What is the maximum number of eggs that Farmer James can buy with $10$ dollars?


[b]p9.[/b] What is the sum of the $3$ leftmost digits of $\underbrace{999...9}_{2018\,\,\ 9' \,\,s}\times 12$?


[b]p10.[/b] Farmer James trisects the edges of a regular tetrahedron. Then, for each of the four vertices, he slices through the plane containing the three trisection points nearest to the vertex. Thus, Farmer James cuts off four smaller tetrahedra, which he throws away. How many edges does the remaining shape have?


[b]p11.[/b] Farmer James is ordering takeout from Kristy's Krispy Chicken. The base cost for the dinner is $\$14.40$, the sales tax is $6.25\%$, and delivery costs $\$3.00$ (applied after tax). How much did Farmer James pay, in dollars?


[b]p12.[/b] Quadrilateral $ABCD$ has $ \angle ABC =  \angle BCD = \angle BDA = 90^o$. Given that $BC = 12$ and $CD = 9$, what is the area of $ABCD$?


[b]p13.[/b] Farmer James has $6$ cards with the numbers $1-6$ written on them. He discards a card and makes a $5$ digit number from the rest. In how many ways can he do this so that the resulting number is divisible by $6$?


[b]p14.[/b] Farmer James has a $5 \times 5$ grid of points. What is the smallest number of triangles that he may draw such that each of these $25$ points lies on the boundary of at least one triangle?


[b]p15.[/b] How many ways are there to label these $15$ squares from $1$ to $15$ such that squares $1$ and $2$ are adjacent, squares $2$ and $3$ are adjacent, and so on?
[img]https://cdn.artofproblemsolving.com/attachments/e/a/06dee288223a16fbc915f8b95c9e4f2e4e1c1f.png[/img]

[b]p16.[/b] On Farmer James's farm, there are three henhouses located at $(4, 8)$, $(-8,-4)$, $(8,-8)$. Farmer James wants to place a feeding station within the triangle formed by these three henhouses. However, if the feeding station is too close to any one henhouse, the hens in the other henhouses will complain, so Farmer James decides the feeding station cannot be within 6 units of any of the henhouses. What is the area of the region where he could possibly place the feeding station?


[b]p17.[/b] At Eggs-Eater Academy, every student attends at least one of $3$ clubs. $8$ students attend frying club, $12$ students attend scrambling club, and $20$ students attend poaching club. Additionally, $10$ students attend at least two clubs, and $3$ students attend all three clubs. How many students are there in total at Eggs-Eater Academy?


[b]p18.[/b] Let $x, y, z$ be real numbers such that $8^x = 9$, $27^y = 25$, and $125^z = 128$. What is the value of $xyz$?


[b]p19.[/b] Let $p$ be a prime number and $x, y$ be positive integers. Given that $9xy = p(p + 3x + 6y)$, find the maximum possible value of $p^2 + x^2 + y^2$.


[b]p20.[/b] Farmer James's hens like to drop eggs. Hen Hao drops $6$ eggs uniformly at random in a unit square. Farmer James then draws the smallest possible rectangle (by area), with sides parallel to the sides of the square, that contain all $6$ eggs. What is the probability that at least one of the $6$ eggs is a vertex of this rectangle?


PS. You should use hide for answers. Collected [url=https://artofproblemsolving.com/community/c5h2760506p24143309]here[/url].
To solve the given problem, we start with the equation:

\[ 9xy = p(p + 3x + 6y) \]

1. **Divisibility by 9:**
   Since \(9\) divides the left-hand side (LHS), it must also divide the right-hand side (RHS). This implies that \(9\) divides \(p(p + 3x + 6y)\).

2. **Prime factor considerations:**
   Since \(p\) is a prime number, we need to consider the divisibility properties. If \(9\) divides \(p(p + 3x + 6y)\), then either \(p\) or \(p + 3x + 6y\) must be divisible by \(9\). However, since \(p\) is a prime number, the only prime number that is a factor of \(9\) is \(3\). Therefore, \(p\) must be \(3\).

3. **Substitute \(p = 3\):**
   Substituting \(p = 3\) into the equation, we get:
   \[
   9xy = 3(3 + 3x + 6y)
   \]
   Simplifying the RHS:
   \[
   9xy = 9 + 9x + 18y
   \]
   Dividing both sides by \(9\):
   \[
   xy = 1 + x + 2y
   \]
   Rearranging the equation:
   \[
   xy - x - 2y = 1
   \]
   Adding and subtracting \(2\) on the LHS:
   \[
   xy - x - 2y + 2 - 2 = 1
   \]
   Factoring the LHS:
   \[
   (x - 2)(y - 1) = 2
   \]

4. **Solving for integer pairs \((x, y)\):**
   We need to find integer pairs \((x, y)\) such that \((x - 2)(y - 1) = 2\). The possible pairs are:
   \[
   (x - 2, y - 1) = (1, 2), (-1, -2), (2, 1), (-2, -1)
   \]
   This gives us the pairs:
   \[
   (x, y) = (3, 3), (1, -1), (4, 2), (0, 0)
   \]

5. **Calculating \(p^2 + x^2 + y^2\):**
   For each pair, we calculate \(p^2 + x^2 + y^2\):
   \[
   \begin{align*}
   (x, y) = (3, 3) & \implies p^2 + x^2 + y^2 = 3^2 + 3^2 + 3^2 = 9 + 9 + 9 = 27 \\
   (x, y) = (1, -1) & \implies p^2 + x^2 + y^2 = 3^2 + 1^2 + (-1)^2 = 9 + 1 + 1 = 11 \\
   (x, y) = (4, 2) & \implies p^2 + x^2 + y^2 = 3^2 + 4^2 + 2^2 = 9 + 16 + 4 = 29 \\
   (x, y) = (0, 0) & \implies p^2 + x^2 + y^2 = 3^2 + 0^2 + 0^2 = 9 + 0 + 0 = 9 \\
   \end{align*}
   \]

6. **Finding the maximum value:**
   The maximum value of \(p^2 + x^2 + y^2\) from the above calculations is \(29\).

The final answer is \(\boxed{29}\)