Question: It takes David 10 minutes to wash 4 windows. David's house has 64 windows. How many minutes will it take David to wash all of the windows?
Answer with step-by-step thinking: It takes 10 minutes to wash 4 windows and he has 64 windows so that breaks down to 64 / 4 = 16 units. It takes 10 minutes to wash a unit of windows and he has 16 units so 10 * 16 = 160 minutes.
So the answer is 160.


Question: Matt needs to buy new plates for his home. He only wants to do dishes once a week. Three days a week it is only him and his son eating and they use 1 plate each. On the remainder of the days, his parents join them and everyone uses 2 plates that day. How many plates does he need to buy?
Answer with step-by-step thinking: So for 3 of the days, there are 1 + 1 = 2 people eating. So for those days they use 3 * 2 = 6 plates. On 7 - 3 = 4 days the parents join them. On those days there are 2 + 2 = 4 people eating. They use 4 * 2 = 8 plates. So they use 8 * 4 = 32 plates. That means they use a total of 32 + 6 = 38 plates.
So the answer is 38.


Question: Rodney is a door-to-door salesman trying to sell home security systems. He gets a commission of $25 for each system he sells. He is canvassing a neighborhood of four streets with eight houses each. The first street gave him half the sales that the second street did, while every house on the third street turned him away and the fourth street resulted in only one sale. His total commission was $175. How many security systems did he sell on the second street?
Answer with step-by-step thinking:
Let S be the number of systems Rodney sold on the first street. He sold 2S systems on the second street. Based on his commission, he sold 175 / 25 = 7 systems. In all, he sold S + 2S + 0 + 1 = 3S + 1 = 7 systems. On the first and second streets, he sold 3S = 7 - 1 = 6 systems. Thus, on the first street he sold S = 6 / 3 = 2 systems. On the second street, Rodney sold 2 * 2 = 4 security systems.
So the answer is 4.