Question

If g(x)=k×f(x) what is the value of k?

Answer 1

k = g(x)/f(x)

Explanation:

Unless there is more to the question, the answer is g(x) / f(x) = k

You just need to divide both sides by f(x)

Here's an example

f(x) = 20x + 40

g(x) = 80x + 160

k = g(x)/f(x) = (80x + 160) / (20x + 40) = 4*(20x + 40)/(20x + 40)

k = 4