Question

Solve this 6r+7=13+7r

Answer 1

  6r + 7 = 13 + 7r
- 6r                - 6r
         7 = 13 + r
    - 13  - 13      
       -6 = r

Answer 2

Let's move all to one side:

6r+7-13-7r=0

and re-arrange  to have similar terms together:
6r-7r +7-13=0

let's add up what we can:

-1r-6=0
we can move the -6 to the other side and multiply both sides by -1 and we get:
r=-6 This is the solution.