Simon and Jimmy had 167 stamps. Simon gave 4/7 of his stamps to Trina, and Jimmy gave 37 stamps to a Trina. Simon and Jimmy had the same number of stamps left. How many stamps did Jimmy have in the beginning?
original number of Simons stamps --- x
original number of Jimmy's stamps --- y
x+y = 167 or y = 167-x
after giveaway:
Simon had (3/7)x
Jimmy had (y-37)
--> it says, those two expressions are the same, so
3x/7 = y-37
times 7
3x = 7y - 259
3x - 7y = -259
subbing in the first equation:
3x - 7(167-x) = -259
3x - 1169 + 7x = -259
10x = 910
x = 91
y = 167-91 = 76
Jimmy had 76 stamps at the start.
