Answer:
a. 
  Taxes to be withheld from Gross Pay (Employee - Paid Taxes)
  September Earnings Tax Rate Tax Amount
 Subject to Tax 
Federal Income tax $80.00
FICA - Social Security 800 6.20% $49.60
FICA - Medicare 800 1.45%  $11.60
Total  $141.20
FICA - Social Security = 800 * 6.2% = $49.60
FICA - Medicare = 800 * 1.45% = $11.60
b. 
Date General Journal Debit Credit
Sep 30 Salaries Expense $800
 Federal income tax payable $80
 FICA taxes Payable - Social Security $49.60
 FICA taxes Payable - Medicare $11.60
 Salaries Payable $658.80
Salaries Payable = 800 - 80 - 49.60 - 11.60 = $658.80