I don't understand what you mean but this might be the answer
13000-5600=7400...that's about it, just multiply then subtract
Answer:
f'(x)=-(x+42)/5
Step-by-step explanation:
Rewrite f(x) as y:
y=-5x-42
Flip x and y and solve for y:
x=-5y-42
x+42=-5y
(x+42)/-5=y
So the inverse function is f'(x)=-(x+42)/5 (note that f' means inverse)