The ratio of the number of marbles Tim has to the number of marbles Peter has is 5:3. If Tim gives 225 of his marbles to Peter, the ratio of the number of marbles Tim has to the number of marbles Peter has will become 7:9. How many marbles does Tim have?

Answer 1

To start with, Tim has 5x and Peter has 3x.
Then we are told that
(5x-225)/(3x+225) = 7/9
x = 150, so
Tim has 5*150 = ____ marbles