Question

< B is:
A) 30°
B) 45°
C) 50°
D) 60°​

Answer 1

m∠B = 50º

Explanation:

B = 180 - (2x + 40) = 180 - 2x - 40 = -2x + 140

C = 180 - (3x - 45) = 180 - 3x + 45 = -3x + 225

From the Exterior Angle Theorem

B + C = 140

-2x + 140 - 3x + 225 = 140

-5x + 365 = 140

-5x = -225

x = 45

-------------------

B = -2x + 140

B = -2(45) + 140

B = -90 + 140

B = 50º

Answer 2

`< b = 180 \degree - (2x + 40)\degree \\ =( 140 - 2x)\degree`