Simon and Jimmy had 167 stamps altogether. Simon gave 4/7 of his stamps to Trina, and Jimmy gave 37 stamps to Trina. Simon and Jimmy had the same number of stamps left. How many stamps did Jimmy have in the beginning?

I need you to show me how you did it because I have trouble with these types of questions.

2 answers

using two variables:

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.
Argghhh, just noticed that I answered this same question back in 2011

http://www.jiskha.com/display.cgi?id=1294093445