You can put this solution on YOUR website!
-20=-4X - 6X
Let's make this look simpler by doing something to make this problem friendlier.
Multiply both sides by -1
-1(-20) = -1(-4X - 6X)
20 = 4X + 6X. Ahhhh, that's better
20 = 10X
Divide both sides by 10 giving ...
2 = X