Line m is parallel to line n. the measure of angle 2 is 64°. what is the measure of angle 5?

Angles 2 and 6 are corresponding angles.
When parallel lines are cut by a transversal, corresponding angles are congruent, so angles 2 and 6 are congruent.
m<2 = m<6 = 64 deg.

Angles 5 and 6 are a linear pair, so they are supplementary, and their measures add to 180 deg.

m<5 + m<6 = 180

m<5 + 64 = 180

m<5 = 180 - 64

m<5 = 116

m<5 = 116 deg.

Cdoes not have two variables

The answer is $9.90 with rounding to the nearest tenth