Question

What is -19=x-7. ? I don't know how to do this

Answer 1

There can only be one reason for that . . . making
something tough out of something easy.

-19  =  x - 7

How could you get 'x' all by itself on one side,
and everything else on the other side ?

What if you add  7  to each side ?

Then you have    -12  =  x    .  To your amazement, that's the solution !

Answer 2

-19=x-7
-19+7=x-7+7
-12=x