To solve a linear equation where there are variable terms on both sides works the same way as solving any equation: we apply the same operation to both sides, intending to isolate one of the terms with the variable. I solve several such equations for examples. You can pause the video and solve these yourself, before I do! We also look at the common student error called "adding or subtracting across sides".
Simplifying Linear Expressions — video lesson
Math Mammoth Grade 8 curriculum