Bill was christmas shopping. He spent 1/2 of his money on a gift for his sister and 1/3 on a gift for his brother. Later that day he spent 2/3 of his remaining money on a present for his mom. Bill had $20 left. How much money did Bill have to start with?

Answer 1

1/2 + 1/3 = 5/6
2/3 of the remaining 1/6 is 1/9
That means that 1/18 is left
x/18 = 20
x = 360