Answer:
138 degrees
Explanation:
I'm assuming you meant measurement of angle 1 = 42 degrees.
If d//m, then angles 1,4,5, and 8 all have to have the same angle measurement. Likewise, angles 2,3,6, and 7 all have to have the same angle measurement.
So, because we know the angle measurement of angle 1, we can use that to calculate angle 2. Because angle 1 + angle 2 = 180 degrees, we can just do 180 - angle 1 to calculate the measurement of angle 2, which would be 138 degrees. Because angle 2 and angle 7 have to be the same measurement in order to have d//m, angle 7 must be 138 degrees.