see the picture attached to better understand the problem
we know that
m ∠ACD=91.5°
m ∠ACD+m ∠ACB=180°-------> by supplementary angles
so
m ∠ACB=180-91.5-----> m ∠ACB=88.5°
m∠CAB+m ∠ACB=90°-----> by complementary angles
so
m ∠CAB=90-88.5-----> 1.5°
m∠ CAB is the new angle at the bottom left side of the door
the answer is
1.5°
