Answer:
y = 11
Step-by-step explanation:
We use the definition of Supplementary Angles and Adjacent Angles.
Step 1: Set up equation 1 (Definition of Supplementary Angles)
5x - 4 +7x - 8 = 180
Step 2: Solve for <em>x</em>
12x - 4 - 8 = 180
12x - 12 = 180
12x = 192
x = 16
Step 3: Plug in <em>x</em>
5(16) - 4
80 - 4
76°
Step 4: Set up equation 2 (Definition of Supplementary Angles)
76 + 9y + 5 = 180
Step 5: Solve for <em>y</em>
9y + 81 = 180
9y = 99
y = 11