You and your friend collect football cards. you tell your friend that you have 3 times the number of cards he has. your friend replies that you only have 80 more football cards then he does. how many cards do you each have?

Easy I guess ..
I ll try to help ..
Here we go ..
The cards you have is N
The cards he has is n
you have 3 times the number of cards he has
This means N=3n
 you only have 80 more football cards then he does
This means N=n+80
But we already know that N=3n
So 3n=n+80
which is 2n=80
n=40
So your friend has only 40 cards and you have 3*40= 120 cards

Best luck

Wise