Question 896473
the angle that is equal to 70 is assumed to be the unnamed angle which i'll call angle C.
the external angle outside of angle B is 120 degrees.
since the external angles of a triangle is equal to the sum of the two remote interior angles, this means that the sum of the two remote interior angles is 120 degrees.
since C is 70, then B must be 50 because 170 + 50 = 120.
angle B is the supplement of the exterior angle and is equal to 60.
your solutions are:
angle A = 50
angle B = 60
unnamed angle = 70.