Final answer:
To find the value of x when f(x) = 5x + 20, set the equation equal to 5 and solve for x.
Step-by-step explanation:
To determine the value of x when f(x) = 5x + 20, we need to solve the equation for x.
Given that f(x) = 5x + 20, we set it equal to the given value of 5 and solve for x:
5x + 20 = 5
Subtracting 20 from both sides, we get:
5x = -15
Dividing both sides by 5, we get:
x = -3
Therefore, the value of x when f(x) = 5x + 20 is -3.