<p>Each day, 3c members sell x bars each, so 3cx bars are sold per day. Over the 5 days, 5(3cx)=15cx bars are sold. Since the problem asks for boxes, divide 15cx by c to get just boxes. In 15cx/c, the c’s cancel, and you’re left with 15x. Answer’s E.</p>
<p>It’s an algebraic word problem.</p>