Answer:
C
Step-by-step explanation:
Exterior angle property: Exterior angle equal the sum of opposite interior angles.
3x + 7 + 4x + 16 = 100
3x + 4x + 7 + 16 = 100 {Combine like terms}
7x + 23 = 100 {Subtract 23 from both sides}
7x = 100 - 23
7x = 77 {Divide both sides by 7}
x = 77/7
x = 11
∠B = 3x + 7 = 3*11 + 7
= 33 + 7
= 40°
