Problem Solving

fangtray wrote:Hello,

I have a tough time on these 2 questions mainly because it is difficult for me to choose which numbers to plug in so that the math is easy and i don't get decimals. Can an expert show me a way to see what numbers to pick? or perhaps a more efficient way to do the problem?

163. This year Henry will save a certain amount of his income, and he will spend the rest. Next year Henry will have no income, but for each dollar that he saves this year, he will have 1 + r dollars available to spend. In terms of r, what fraction of his income should Henry save this year so that next year the amount he has available to spend will be equal to half the amount that he spends this year?

a. 1 / r+2
b. 1 / 2r+2
c. 1 / 3r+2
d. 1 / r+3
e. 1 / 2r+3

fangtray wrote:Hello,

I have a tough time on these 2 questions mainly because it is difficult for me to choose which numbers to plug in so that the math is easy and i don't get decimals. Can an expert show me a way to see what numbers to pick? or perhaps a more efficient way to do the problem?

204. John and Mary were each paid x dollars in advance to do a certain job together. John worked on the job for 10 hours and Mary worked 2 hours less than John. If Mary gave John y dollars of her payment so that they would have received the same hourly wage, what was the dollar amount, in terms of y, that John was paid in advance?

a. 4y
b. 5y
c. 6y
d. 8y
e. 9y


I got both of these problems correct, but with brute force plugging in different numbers. Please help!