Answer:
b=85º
a=20º
Explanation:
Angle B is supplementary with the 45º and the 50º angle, therefore the sum of the three angles must be 180
45+b+50=180
95+b=180
b=85º
Angle A, Angle B, and the 75º angle must also add up to 180
85+75+a=180
160+a=180
a=20º