Answer:
<B=45°
Step-by-step explanation:
<A=<B (alternate angles)
5x-15=2x+21
5x-2x=21+15
3x=36
Dividing both sides by 3
x=12
Now.
<A=5(12)-15
=60-15
=45°
Now
<B=2(12)+21
=24+21
[tex]m \angle A = m \angle B\\.. (Exterior \:alternate \: \angle 's) \\ \therefore \: 5x - 15 \degree = 2x + 21 \degree \\ \therefore \: 5x -2x = 21 \degree +15 \degree \\ \therefore \: 3x = 36 \degree \\ \therefore \: x = \frac{6 \degree }{3} \\ \therefore \: x = 12\degree \\ m \angle B = 2x + 21 \degree \\ = 2 \times 12\degree + 21 \degree \\ = 24\degree + 21 \degree\\ \huge \red { \boxed{\therefore \: \ m \angle B = 45 \degree}}[/tex]
