Find the measure of angle x

triangle xyz is isosceles. The base angles, angle x and angle y, are four times the measure of the vertex angle, angle Z .

x = 4z
y = 4z
x + y + z = 180
4z + 4z + z = 180
9z = 180
z = 180/9
z = 20
x = 4*20 = 80
y = 4*20 = 80