The values of $r, s, t$, and $u$ are $2,3,4$, and 5 , but not necessarily in that order. What is the largest possible value of $r \times s+u \times r+t \times r$ ?
(A) 24
(B) 45
(C) 33
(D) 40
(E) 49
We first recognize that in the products, $r \times s, u \times r$ and $t \times r, r$ is the only variable that occurs in all three.

Thus, to make $r \times s+u \times r+t \times r$ as large as possible, we choose $r=5$, the largest value possible.

Since each of $s, u$ and $t$ is multiplied by $r$ once only, and the three products are then added, it does not matter which of $s, u$ or $t$ we let equal 2,3 or 4 , as the result will be the same. Therefore, let $s=2, u=3$ and $t=4$.

Thus, the largest possible value of $r \times s+u \times r+t \times r$ is $5 \times 2+3 \times 5+4 \times 5=10+15+20=45$.

ANSWER: (B)