Triangle ABC is isosceles with angle B congruent to angle C. The measure of angle C is four times the measure of angle A. What is the number of degrees in the measure of angle B?
If angle A=x, then: Angle C =4x. But you have: B=C. Therefore: x + 4x + 4x = 180 degrees 9x = 180 x =180/9 =20 degrees - which is angle A. Angle B =Angle C = 4 x 20 = 80 degrees.