Two angles are called complementary when their measures add to 90 degrees.
So:
∠A = ∠B - 22° (1)
∠A + ∠B = 90° (2)
We need to solve the equation's system, as follows:
From eq 1. we have solved for ∠A; so replacing it on eq 2:
∠B - 22° + ∠B = 90°
2∠B - 22° = 90°
2∠B = 112°
∠B = 56°
Replacing it on eq 1:
∠A = 56° - 22°
∠A = 34°
