Final answer:
To find the missing angle between parallel lines, subtract the given angle from 180 degrees.
Step-by-step explanation:
To find the missing angle between parallel lines, we can use the property that alternate angles are equal when a transversal intersects parallel lines. The missing angle can be found by subtracting the given angle from 180 degrees. For example, if the given angle is 60 degrees, the missing angle would be 180 - 60 = 120 degrees. This is because alternate angles are congruent.