Question

ABCD is a parallelogram. If angle B is equal to (2x)° and angle A is equal to (-x + 120)°, find x.

Answer 1

In parallelograms, the two adjacent angles always add up to 180. So, that means that angle A + angle B = 180:

2x + (-x + 120) = 180

Solve for x:

x = 60