remember you can do anything to an equation as long as you do it to both sides
in this question, we want to solve for r
minus 8q both sides
8q-8q+2r=2q-8q+4
0+2r=-6q+4
2r=4-6q
divide both sides by 2
(2r)/2=(4-6q)/2
r(2/2)=(4/2)+(-6q/2)
r(1)=2+(-3q)
r=2-3q
