I WILL GIVE BRAINLIEST IF TWO PEOPLE ANSWER! PLEASE PUT WHAT X IS, AND PLEASE PUT THE REASONS OF HOW YOU DID IT, FOR INSTANCE, SUBSTITUTION, OR ALTERNATE INTERIOR ANGLES

I WILL GIVE BRAINLIEST IF TWO PEOPLE ANSWER PLEASE PUT WHAT X IS AND PLEASE PUT THE REASONS OF HOW YOU DID IT FOR INSTANCE SUBSTITUTION OR ALTERNATE INTERIOR AN class=