How do input this in excel

If an employee has a taxable income(f4) of greater than $739, then the federal tax withheld equals $110.85 plus the federal tax rate found in cell b19 multiplied by the taxable income (f4) in excess of 739. If an employees taxable income is $739 or less, the federal tax withheld equals the taxable income multiplied by the federal tax rate found in cell B18. Use the IF function to calculate the federal tax in Column I