Question

If ∠AOB, ∠BOC, and ∠COD are supplementary angles, then what is the value of x and m∠COD?

A.
x = 20; m∠COD = 50°
B.
x = 20; m∠COD = 70°
C.
x = 50; m∠COD = 20°
D.
x = 30; m∠COD = 80°

Answer 1

B

Explanation:

∠ AOB + ∠ BOC + ∠ COD = 180° ( AOD is a straight line ) , then

20 + 90 + x + 50 = 180 , that is

x + 160 = 180 ( subtract 160 from both sides )

x = 20

Then

∠ COD = x + 50 = 20 + 50 = 70°

Answer 2

B

Explanation:

x=180-90-20-50=20

m∠COD=20+50=70