Consider the question. Ned opens a left-handed store. He sells left-handed mice. They cost 30% more than normal mice. He sells 25 a day and his store is open every day except Sunday, Thursday, and Friday. If normal mice cost $120 how much money does he make a week?
 If the answer is '15600'; explain the reasoning:
The left - hand mice cost 120 * .3 = $36 more than right - handed ones. So they cost 120 + 36 = $156. So he makes 156 * 25 = $3900 a day. The store is open 7 - 3 = 4 days a week. So in a week, he makes 3900 * 4 = $15,600.