Because of the lines on each side of the rhombus, that shows you that all of those lines are congruent with each other, meaning they are all the same length. So since one side equals the other, you can equal one of the equations on one side to another equation on another side. EX: x+5 = 3x-1. And then you solve that through multi-step equations.
Problem 4:
Just like on Problem 3, due to the little dashes going through the sides of the rectangle, the sides are congruent (the same length) as one another. Except the sides with one dash are not congruent with the sides with two dashes. But if you equal 2y and y+8, then you can solve that through multi-step equations again and get y = 8 since they are congruent with each other (due to the singular dashes running through their sides).
