Math
posted by Camille .
A vendor sold 1/3 of his fish balls in the afternoon and 2/5 of the remainder in the evening. If he had 150 fish balls left, find the number of fish balls he had at first?

let the number of fish at the start be x
sold (1/3)x in the afternoon, leaving his with (2/3)x
He sold 2/5 of that leaving him with
(3/5) (2/3)x or (2/5)x
(2/5)x = 150
x = 375
check:
sell 1/3 of 375 = 125 , leaves 250
sells 2/5 of that or 100 , leaving him with 150
All is good! 
n  n/3  2/5 (2n/3) = 150
n  n/3  4n/15 = 150
(15  5  4)n/15 = 150
6n/15 = 150
2n/5 = 150
n = 375
check:
sold 1/3 of 375 = 125, leaving 250
sold 2/5 of 250 = 100, leaving 150