Eugene and Frank had a total of 272 stamps. Eugene gave 1/3 of his stamps to Frank. Frank then gave 1/5 of his stamps to Eugene. In the end, each of them had the same number of stamps. How many stamps did Eugene have at first?
If both have the same number at the end then each has (272/2) = 136
Let E be the number that Eugene started with and F what Frank started with
And F = 272 - E
Eugene gives away (1/3) of his
And from Frank he gets (1/5) ( F + (1/3) E ) = (1/5) ( 272 - E + (1/3)E ) (2)
So at the end, what Eugene started with - what he gave away + what he got from Frank = 136
So
E - (1/3)E + (1/5) [ (272 - E + (1/3)E ] = 136
(2/3)E + 272/5 + (1/5)(-2/3)E = 136
(2/3)E - (2/15)E = 136 - 272/5
[ 8/15] E = 408 / 5
8E = 1224
E = 153 = stamps that Eugene started with
And Frank started with 119
Proof
Eugene gives (1/3) to Frank = (153) / 3 = 51
Eugene now has 102
And now Frank has 119 + 51 = 170
He gives 1/5 of these to Eugene = 34
Eugene now has 102 + 34 = 136
Frank now has 119 + 51 - 34 = 136