Question

If m angle abf=7b-24 and m angle abe=2b find m angle ebf

Answer 1

angle ABE is equivalent to the whole angle, and it measures 2b. 
while the angle ABF is only a portion of angle ABE, and it measure 7b - 24. 

since we know the measure of the whole angle and a part of the angle, we can then subtract to find the left over angle (angle EBF), so

Angle EBF = Angle ABE - Angle ABF 

Angle EBF = 2b – (7b – 24)

Angle EBF = 24 – 5b