Question 1019733
i'm inclined to say This question is missing some details, please edit and resubmit. But I'm going to guess, a right triangle?

m<A+m<D =90 

x + 18 + 2x = 90

3x+18 =90

3x = 72

x=24

m<A = x + 18 = 24 +18= 42
m<D = 2x = 2*24= 48