Answer:
Step-by-step explanation:
∠EMC = ∠EMD + ∠DMC
∠EMC = 90
∠EMD + ∠DMC = 90
∠EMD + 20 =90
∠EMD = 90 - 20
∠EMD = 70
∠FMD + ∠DMB = 180 {Linear pair}
90 + ∠DMB = 180
∠DMB = 180 - 90
∠DMB = 90
