The sum of the angles of a triangle must equal 180.
A + B + C = 180
50 + B + C = 180
B + C = 180 - 50
B + C = 130
If B and C are equal to each other, we can just divide 130 by 2 to find the other two angles.
130 / 2 = 65
Angles B and C are both 65 degrees