The weight of box A is 4/5 of box B. If box B is placed on one side of a balance scale, it is balanced by box A and a 4/5 pound weight. How much does box B weigh?
ah- much better. We need
4/5 B + 4/5 = B
4/5 = 1/5 B
B = 4
Check: On Box A's side, we have
4/5 * 4 + 4/5 = 16/5 + 4/5 = 20/5 = 4