The measure of an angle that is its own supplement is

90 degrees

Explanation:

Let x and y be the two angles. Because they are supplementary angles, this means x+y = 180. Also since we're told that the angle is its own supplement, we can say that y = x.

Consequently, we can replace y with x and solve for x like so:

x+y = 180

x+x = 180 y is replaced with x since y = x

2x = 180

2x/2 = 180/2

x = 90

This means y = 90 as well. As a check, note how

x+y = 90+90 = 180

which verifies our answer.

45

step-by-step explanation: