how did they get 43? I know they simplified but I still don't get it

Question

y+6=-7/13x+35/13 simplified is y=-7/13x-43/13  

Answer 1

The six on the left side of the equation goes over to the right side, as -6, and that is -78/13.*

It then combined with 35/13 to yield -43/13.

 

* this process is called transposing a term, and is equivalent to subtraction of a value from each side.