Question

Find the measure of angle R.

Answer 1

64 + 2x = 180
2x = 116
x = 58

angle R equals 58 degrees

Answer 2

Hi! let's go: 

The measures of interior angles of a triangle sum to 180°... ok?
According to the figure, Q and R have equal measure  >>> X <<< 

So,           64° + 2X = 180°
                2X = 180° - 64°
                2X = 116
                  X = 116 / 2
                  X = 58 

As a result, angle R equals 58°

:)