Question 850408
let the number of stamps Peter has be x and then John has 4x
now John got 13 more stamps and Peter got 7, therefore
(4x+13) / (x+7)  =  3/1
now cross multiply the fractions
4x+13 = 3*(x+7)
4x+13 = 3x+21
x = 8
at first Peter had 8 stamps and John had 32 stamps