4)In triangle ACM,
Angle C= 180-(angle A+angle M)
= 180-(50+90)
= 180-140
= 40
In triangle CMB,
Angle B= 180-(angle C+angle M)
=180- (40+90[linear pair])
= 180-130
= 50
In triangle ABC,
Angle B = 50
Angle C = 40
2) The question is incomplete, it does not state what to find or solve.