Jim spent 3/8 of his money on eggs. he spent 2/5 of the rest of his money on butter. he had $6.72 left. how much money did him start with?

First make the denominator equal for both fractions.
The LCM of 8 and 5 is 40, so 40 will be the common denominator.
3/8=15/40 and 2/5=16/40
Add them together.
15/40+16/40=31/40
He has 9/40 of his money left, which means 9/40 of the total money=$6.72
Make an equation to solve for how much money he had when he started (x).
6.72/x=9/40
After solving, x= about $29.87