Alex spent 3/7 of his money. He gave 1/4 of the remainder to his sister. He had $120 left. How much money did he have in the beginning?

Question

phi · Answer

you should change the English into "math"

start with
 How much money did he have in the beginning? 
call it x  (unknown amount that he started with)

he spent 3/7 of his money.   
replace "his money" with x:

3/7 of x
which is written as 3/7 * x

he started with x, and spent 3/7 x :  
$ x - \frac{3}{7} x $ 
is how much he has left



 gave  1/4 of the remainder to his sister.
1/4 of the remainder is
$ \frac{1}{4}\left(x - \frac{3}{7} x\right) $ 

$$  x - \frac{3}{7} x -\frac{1}{4}\left(x - \frac{3}{7} x\right) = 120$$

anonymous · Answer

Oh! I get it now. Thanks a bunch! :]