A student had an amount of $P at the beginning of a semester. He spent 1/3 of the amount on books and 3/5 of the remainder on snacks. If $400.00 was left at the end of the semester , find the value of P.

Answer 1

1 had P
2 spent 1P/3 on books, 2P/3 left
3 spent 3/5 * 2P/3 = 2 P/5 on snacks 2/5 * 2 P/3 = 4 P/15 left
so
4 P/15 = 400
P = 1500

Answer 2

2/3P - .6P = 400

Solve for P.