Answer:
d = 90°, e = 100°, f = 80°
Explanation:
d:
Angle d and the labeled angle on the other side of it are supplementary angles, meaning they add up to 180°. The square icon on the other side of d means that the angle is 90°. This makes it easy to figure out; all you have to do is 180-90, which gets you d = 90°.
e:
You can figure out e with vertical angles. Since it's corresponding vertical angle is 100°, that makes e = 100°.
f:
Similar to d, you can figure out angle f because f and the 100° angle. You can come up with the equation 100° + f = 180°, which gets you 80°.