Find angle ADB of the equation

Answer:
[tex]m\angle ADB = 59\°[/tex].
Step-by-step explanation:
Given:
[tex]\angle BDC = 31\°[/tex]
We need to find [tex]\angle ADB[/tex].
Solution:
Now we can see that given figure is a rectangle with diagonals drawn in it.
So by properties of rectangle which states that;
"All angles of a rectangle are 90°."
So we can say that;
[tex]\angle A = \angle B = \angle C = \angle D = 90\°[/tex]
But
[tex]\angle D = \angle BDC + \angle ADB[/tex]
Substituting the values we get;
[tex]31\°+\angle ADB = 90\°[/tex]
Subtracting both side by by 31 we get;
[tex]31\°+\angle ADB -31\°= 90\°-31\°\\\\m\angle ADB = 59\°[/tex]
Hence [tex]m\angle ADB = 59\°[/tex].