Mr Lee spent 1/12 of his money on a.belt and 1/4 of it on books. He had $240 left. How much did he spend on the books?
amount spent = 1/12 + 1/4 = 1/3
So (2/3) of his money is left
(2/3)x = 240
x = 240(3/2) = 360
so he spent (1/4)(360) or $90 on books