Section: Mathematical Reasoning

18) Two supplementary angles have measures of 9x degrees and 3x degrees. What is the measure of the longer angle? 

1. 180 degrees
2. 45 degrees
3. 135 degrees
4. 15 degrees

Supplementary angles must add up to 180 degrees. Using that logic, you can solve for x.

9x + 3x = 180
12x = 180
x = 15

Now plug 15 in to 9x and 3x individually, and your two angles will be 135 degrees and 45 degrees. Answer 3 is correct since you want the longer angle.