Brain Teaser from my school agenda

Question

if sam gives 7 baseball cards to lee, lee will then have 5 times as many cards as sam. However, if lee gives sam 7 baseball cards, both will have the same number of cards. How many cards does each currently have?

Answer 1

Let x = number of cards that Sam has now

y = number of cards that Lee has now

Then y + 7 = 5(x - 7) and x + 7 = y - 7.

So, x - y = -14 and 5x - y = 42

Subtract the first equation from the second to get: 4x = 56.

So, x = 14 and y = 28.

Sam has 14 cards and Lee has 28.