ACD is a straight line= 180 degrees.
If angle BCD= 113 degrees,
then angle BCA= 180 - 113 degrees
= 67 degrees.
Sum of interior angles of a triangle= 180 degrees.
So, angle B= 180 - (72 + 67)
= 180 - 139
= 41 degrees.
Therefore, angle B = 41 degrees.
I hope I'm right :)
