How do I go about answering this?

Question

Given y=2z² - 1 and z=-4/x find dy/dx when x=2?

Answer 1

y = 2z^2-1 = 2(-4/x)^2-1 = 2(16/x^2)-1 = 32/x^2 -1

y' = dy/dx = -64/x^3

y'(2) = -64/2^3 = -64/8 = - 8

dy/dx when x = 2 is - 8