Answer:
Simplifying
f(x) = 5x + -20
Multiply f * x
fx = 5x + -20
Reorder the terms:
fx = -20 + 5x
Solving
fx = -20 + 5x
Solving for variable 'f'.
Move all terms containing f to the left, all other terms to the right.
Divide each side by 'x'.
f = -20x-1 + 5
Simplifying
f = -20x-1 + 5
Reorder the terms:
f = 5 + -20x-1
Explanation: