There are a few approaches. One way is to note that angles 1 and 3 combine to 180
angle1+angle3 = 180
132+angle3 = 180
angle3 = 180-132
angle3 = 48
This is also equal to the measure of angle 6. Angles 3 and 6 are congruent when we have parallel lines like this (since they are alternate interior angles).