Harrh gives 0.6 of his marbles to his younger brother and 0.5 of the remainder to his cousin. Harry has 36 marbles left. How many marbles did Harry have at first?

Answer 1

starting number ---- x
after giving to younger brother, number left = .4x
gives away half of that, so left with .2x
.2x = 36
x = 36/.2 = 180