Two angles are said to be supplement when their measure add up to 180 degrees.
Assume that the angle we are looking for is a and its supplement is s (I used s instead of x).
a + s = 180
a = 180 - s ......> equation I
We know that the measure of the angle is eight times greater than its supplement.
This means that:
a = 8s ......> equation II
Substitute by equation II in equation I to get s as follows:
180 - s = 8s
180 = 9s
s = 20 degrees
Substitute in equation I to get the measure of the angle as follows:
a = 180 - s = 180 - 20 = 160 degrees
Based on these calculations:
The measure of the angle is 160 degrees
The measure of its supplement is 20 degrees