an angle is equal to one-third of its supplemet. find its measure

Match the items on the right to the items on the left.

step 1

step 2

step 3

step 4

step 5

step 6

let the measure of the angle be x°

then, the measure of its supplement is (180-x)°

from given, x=1∕3*(180-x)

3x=180-x

2x=180

x=90