Let
p(x) = x - 2y
What is p(p(1,-1),p(-5,-2))?
p(1,-1) = 1 - 2(-1) = 3
p(-5,2) = -5 -2(2) = -9
So we have
p (3, -9) = 3 - 2 (-9) = 3 -18 = -15
