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I need help doing an If statement in excel 2013. I have done everything up till 14, 15-17 is the problem.

15) Overhead costs include maintenance, cleaning, and administrative expenses associated with a car rental. The Overhead for one rental transaction is $50 for an economy car and $75 for a premium car. This Overhead cost includes maintenance, cleaning, and administrative costs for each car rental. a. With this information, in the Profit Analysis worksheet, in the first cell under the Overhead label, calculate the overhead that corresponds to the number of cars rented (NumCars) using an "IF" statement as part of the formula. b. For clarification, use the "IF" statement to determine whether to use $50 or $75 times the NumCars so that the Overhead value represents the total Overhead costs for the Number of Cars (NumCars) rented in a given row. 

16) In the Profit Analysis worksheet: a. Copy the overhead formula to all the cells below in the Overhead column. Adjust the column width if necessary for legibility. b. Ensure overhead data format is Currency ($ and using comma as thousands separators) with NO decimal points. Note: Each row in the new column must have the same general appearance (color, shading) as the other cells to its left in that same column.

17) In the Profit Analysis worksheet: In the next column to the right of the Overhead label,

18) In the Profit Analysis worksheet, profit represents the difference between Revenue and Overhead (Revenue - (minus) Overhead) for the data IN the same row as the profit data shown. Profit is for all cars rented during the quarter. In the first cell below the label Profit: a. Calculate the profit, b. Then copy the formula for all cells in that column (if necessary). c. Adjust the column width if necessary for legibility. Note: If you are clicking on cells to construct a formula, you may see [@Revenue]-[@Overhead in the cell editor, a result of using an Excel table. In Excel, there are often many different ways to accomplish the same task. Double-checking the calculation with a hand-held calculator can identify possible errors. Note: Each row in the new column must have the same general appearance (color, shading) as the other cells to its left in that same column.

Here is a copy of my excel work sheet