Geometry

Since angle(BAC) = 21^o     --->     angle(QAD) = 69^o     --->     angle(QDA) = 21^o.

Since triangle PDC is an isosceles triangle, and AB is parallel to DC because it is a rectangle, then that means angle DCP is congruent to angle BAC. So angle PCD is 21*. Angle PDC is also 21*.

Angle DAQ is 90 - 21 = 69*. So QDA is 180-90-69 = 21 degrees. Since we are looking for the sum of angles PDC and angle QDA, the answer is 42*.