Tax credits provide dollar for dollar reduction of the persons income. meaning $1,000 tax credit saves $1,000 taxes.
Tax deductions lower taxable income and then they equal the % of the persons marginal tax bracket
THE WAY YOU CHACK THE ANSWER IS BY SUBTRACTING 31-17 AND SEEING IF IT GIVES YOU 14 OR THE OTHER WAY AROUND
Since a yard is 3 feet, then 3 times 3 is 9 and that is less than 21.