In the given figure, we can see that ∠MBA is vertically opposite to the angle ∠CBN.
Therfore, ∠MBA = ∠CBN = 45⁰
Also, ∠PDA is vertically opposite to the angle ∠QDE.
Therfore, ∠PDA = ∠QDE = 45⁰
Hence the sum of the angles ∠MBA and ∠PDA is 45⁰ + 45⁰ that is equal to 90⁰.