Question 9The point $P(a,b)$ in the $xy$-plane is first rotated counterclockwise by $90^\circ$ around the point $(1,5)$ and then reflected about the line $y = -x.$ The image of $P$ after these two transformations is at $(-6,3).$ What is $b - a ?$$ 1 $$ 3 $$ 5 $$ 7 $$ 9 $