Final answer:
The correct function notation for Charles' babysitting situation is f(x) = 4 + 7x.
Step-by-step explanation:
The correct answer is f (x) = 4 + 7x (option d).
The function notation f(x) represents a function that takes an input value x and returns an output value f(x). In this case, the function is representing Charles' babysitting situation. The equation f(x) = 4 + 7x represents the total fee earned by Charles for babysitting x number of hours.
For example, if Charles babysits for 3 hours, the fee earned can be calculated by substituting x = 3 into the equation f(x) = 4 + 7x:
f(3) = 4 + 7(3) = 4 + 21 = 25
Therefore, the fee earned by Charles for babysitting 3 hours is $25.