What is the justification for -3x+7=7x-3

Create a real-life situation and create a system and show how it might be modeled algebraically with a system of equations (or inequalities) show all work include a few sentences explaining the situation, your variables of choice and what each represents, and how you would set it up and solve it algebraically. !

Name each raycalculation tip: in ray "ab", a is the endpoint of the ray.

The measure of one angle of an octagon is two times smaller that of the other seven angles. what is the measure of each angle?