If the measure of angle d is 5 times the measure of angle e, then:
d = 5e
Now, we also know the two angles are supplementary (add to 180). So:
d + e = 180
To solve, substitute what d is in the 1st eq (5e) for d in the 2nd eq. Then:
5e + e = 180 => 6e = 180 => e = 30.
If e = 30, then d must be 180 - 30 = 150.
