2007 AMC 10B Problems/Problem 2

Problem

Define the operation $\star$ by $a \star b = (a+b)b.$ What is $(3 \star 5) - (5 \star 3)?$

$\textbf{(A) } -16 \qquad\textbf{(B) } -8 \qquad\textbf{(C) } 0 \qquad\textbf{(D) } 8 \qquad\textbf{(E) } 16$

Substitute and simplify. $(3+5)5 - (5+3)3 = (3+5)2 = (8)2 = \boxed{\textbf{(E) }16}$

2007 AMC 10B (Problems • Answer Key • Resources)
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