Answer:
x=13
Step-by-step explanation:
Angle A and angle B are supplementary
Supplementary angles add to 180 degrees
<A + <B = 180
7x-18 + 8x+3 = 180
Combine like terms
15x -15 = 180
Add 15 to each side
15x-15 +15 = 180+15
15x = 195
Divide by 15
15x/15 =195/15
x =13
