URGENT! prep math 2Qs

mizhang9

PS
A‘s take-home pay last year was the same each month, and she saved the same fraction of her take-home pay each month. the total amount of money that she had saved at the end of the year was 3 times the amount of that portion of her monthly take-home pay that she did not save. If all the money that she saved last year was from her take-home pay, what fraction of her take-home pay did she save each month?

key is 1/5, no idea >< guess my interpretation of the highlighted sentence is mistaken...

DS
A contractor combined x tons of a gravel mixture that contained 10% gravel G, by weight, with y tons of a gravel mixture that contained 2% gravel G, by weight,to produce z tons of a gravel mixture that contained 5% gravel G, by weight,wats the value of x?
1. y=10
2. z=16

key is D. need help

with many thx!

mizhang9

upup

xiaccao

1) 12*x%*Salary=3*(1-x%)*Salary  x=1/5

kc8282

2) 0.1x + 0.2y = (x+y) 0.5

condition 1, y is known, then only x is left in the equation, hence x is solvable.
condition 2, z is know, and is the same as x+y, so x=16-y. Again, only x is left in the equation, hence is solvable.

D.

geekland

Q2:  10%*x + 2% y= 5% (x+y) ; z=x+y

I think this question is rather a word game than math.

Good luck!