Answer
B = $45^{\circ}$
Work Step by Step
In right triangle CDB-
Given acute angle C = $45^{\circ}$ and B is also an acute angle.
We know that acute angles of a right triangle add up to $90^{\circ}$
Therefore
B + C = $90^{\circ}$
B + $45^{\circ}$ = $90^{\circ}$
B = 90 - 45 = $45^{\circ}$
