Determine the instantaneous rate of change of f(x)=x/x-2 , at x=-5

review the derivative. That is the rate of change.

use the quotient rule.
f'(x) = -2/(x-2)^2

or, note that f(x) = 1 + 2/(x-2)
so that f'(x) = -2/(x-2)^2

now find f'(-5)