(Question 3)
Because of the definition of a perpendicular bisector, we know that angle B is a right angle (90°) an that

Note that AB is a segment that is shared by both triangles in the image. By using SAS (Side-Angle-Side), we can find that both the triangles are congruent (they are equal). Therefore,

We know that

We'll just have to plug in the value of x we calculated to find the lenght of AE

Therefore, AE = 36
(Question 4)
Because of the definition of a perpendicular bisector, we know that XY splits TS right by the middle. So if TS = 10, RS would be worth half of that
Therefore, RS = 5