Ali, Benny and Charles had 255 stamps altogether. Ali gave 3/8 of his stamps to Benny and 1/5 of them to Charles. After that, all the three boys had the same number of stamps. How many more stamps did Charles have than Benny at first?
a+b+c = 255
b + 3/8 a = c + 1/5 a
b + 3/8 a = (1 - 3/8 - 1/5) a
solve for a,b,c as usual, then get c-b = 35