Calculate federal and state income tax withholding for a number of employees of TCLH Industries, a manufacturer of cleaning products. Use the wage-bracket method when it is possible to do so, and use the percentage method in all other instances. Assume the state income tax withholding rate to be 5% of taxable pay (which is the same for federal and state income tax withholding).

1. Zachary Fox does not make any voluntary deductions that impact earnings subject to federal income tax withholding. He is married, claims four withholding allowances for both federal and state, and his weekly gross pay was $1,162.
2. Calvin Bell makes a 401(k) retirement plan contribution of 6% of gross pay. He is single, claims two federal withholding allowances and one state withholding allowance, and his weekly gross pay was $417.93.
3. David Alexander makes a 401(k) retirement plan contribution of 12% of gross pay. He is single, claims one withholding allowance for both federal and state taxes, and his weekly gross pay was $4,050.
4. Michael Sierra contributes $50 to a flexible spending account each period. He is married, claims four federal withholding allowances and three state withholding allowances, and his weekly gross pay was $2,450.

My question is how do I calculate Federal income tax withholdings for these individuals?