Question

the measure of an angle exceeds three times the measure of its supplement by 20 degree. find its measure​

Answer 1

An angle and it's supplement add to 180 degrees: A + As = 180.

The supplement of an angle As = 180-A

A = 3As +20 substitute 180-A in place of As

A = 3(180-A)+20 distribute 3 through the parenthesis

A = 540-3A+20 add 3A to both sides

4A = 560 divide both sides by 4

A = 560/4

A = 140 degrees

Check answer:

As = 180-140 = 40 the supplemental angle is 40 degrees

A = 3As+20

140 = 3(40)+20

140 = 140