If the degree measure of an angle is 40 less than 3 times the degree measure of its supplementary angle, what is the degree measure of the angle?

a. 50

b. 55

c. 125

d. 130

The degree measure of angle let being x so than given

x = 3*y - 40

y+x = 180 = > y = 180 - x substitute this value of y inside first equation

x = 3 * (180 - x) - 40

x = 540 - 3x - 40

4x = 500

x = 500/4 = 125

x = 125 degrees so choice c. is right sure