Question

I’m confused on this one

Answer 1

E is the bisector point of AB. Perpendicular bisector means a line that cuts another line in half and meets it at the bisector point at right angles. 

Bisect means cut in half.
AE is 20
Therefore EB = 20 as well. It's the other half of the line.

Answer 2

According to the bisector theorem if angle a f = b f

Then a e = b e

So b e = 20