here you have a vertical angle, so to simply put it the answer on one side of the angle is the same answer for the opposite side of the angle. knowing this, angle <AFE is 62° and <CFD is on the opposite side making the angle the same(62°). the opposite angle of <AFB is <EFD which is 118° but both <AFB and <AFC equal 118° so you subtract 118° to <AFC degree which is 28° and you get 90°.
i hope this makes sense im not good at explaining. if anyone has a better explanation feel free to correct me.
