Anwser: 41°
Okay so every triangle is 180° degrees in total.
We need to find the angle of x in the triangle BDC.
We know that the angle of x is 180 - ( x + 15)
We also have another triangle named BAD
Which angles are 90 + 56 + x
the angle of D in the triangle BDC is 180 -58 = 124
So 124 + 15 = 139
180 - 139 = 41