Every straight line is 180 degrees, meaning that the angle of ∠ABE and ∠CBE must add up to 180. You can say that ∠ABE + ∠CBE = 180. If you rearrange, you can see that ∠ABE = 180 - ∠CBE. Since ∠CBE is given as 63, all you need to do is subtract this from 180 to get 117.
