Question

If f(x)= 5x +40 what is f(x) when x= -5

Answer 1

f(-5)=5(-5)+40
f(-25)=5+40.
f(-25) is your answer.

Answer 2

To find the answer, you would substitute -5 in for each x. The equation would look like this: f(x)=5(-5)+40. The answer is 15. Hope this helps!