The value of $k \nabla m$ is defined to be $k(k-m)$. For example, $7 \nabla 2=7(7-2)=35$. What is the value of $(5 \nabla 1)+(4 \nabla 1)$ ?
(A) 9
(B) 84
(C) 20
(D) 32
(E) 72
From the definition, $(5 \nabla 1)+(4 \nabla 1)=5(5-1)+4(4-1)=5(4)+4(3)=20+12=32$.

ANSWER: (D)