A farmer has 7 cows, 8 sheep and 6 goats. How many more goats should be bought so that half of her animals will be goats?
(A) 18
(B) 15
(C) 21
(D) 9
(E) 6
A farmer has 7 cows, 8 sheep and 6 goats. How many more goats should be bought so that half of her animals will be goats?
(A) 18
(B) 15
(C) 21
(D) 9
(E) 6

## Solution 1

If the cows and sheep were themselves goats we would have 15 goats. This means that she would need nine extra goats.

## Solution 2

Let the number of goats added be $x$.

Therefore, $\frac{6+x}{21+x}=\frac{1}{2}$.

Cross multiplying gives,

$$
\begin{aligned}
2(6+x) & =21+x \\
12+2 x & =21+x \\
x & =9
\end{aligned}
$$

As in solution 1, she would add 9 goats.

ANSWER: (D)