I am thinking of a number i multiply it by 6 and add 104 i get the same answer if i multiply by 13 and subract 8 What is my number ?

variables on one side, constaints on other side,

13x-6x=104+8

simplify

7x=112

divide by 7

x=16.

(I think, I'm only in 7th grade and I'm new to this,so I'm not as smart as CPhill, so try to get a second opinion)

Looks good , fuhsaha !