Question: Sam bought a dozen boxes, each with 30 highlighter pens inside, for $10 each box. He rearranged five of these boxes into packages of six highlighters each and sold them for $3 per package. He sold the rest of the highlighters separately at the rate of three pens for $2. How much profit did he make in total, in dollars? Think carefully first, then make a decision:
Sam bought 12 boxes x $10 = $120 worth of highlighters. He bought 12 * 30 = 360 highlighters in total. Sam then took 5 boxes 6 highlighters / box = 30 highlighters. He sold these boxes for 5 * $3 = $15. After selling these 5 boxes there were 360 - 30 = 330 highlighters remaining. These form 330 / 3 = 110 groups of three pens. He sold each of these groups for $2 each, so made 110 * 2 = $220 from them. In total, then, he earned $220 + $15 = $235. Since his original cost was $120, he earned $235 - $120 = $115 in profit. So the answer is 115.