Answer
See below:
Work Step by Step
(a)
In order to calculate FICA taxes, multiply wages with the tax rate.
\[\begin{align}
& \text{FICA}\,\text{taxes}=\text{Wages}\times \text{Tax}\,\text{rate} \\
& =\$20,000\times\frac{5.65}{100}\\&=\$20,000\times0.0565\\&=\$1,130\end{align}\]
(b)
In order to calculate income tax, first calculate taxable income by deducting the sum of exemptions and deductions from adjusted gross income.
\[\begin{align}
& \text{Taxable}\,\text{income}=\text{Adjusted}\,\text{gross}\,\text{income}-\left( \text{Exemptions}+\text{Deductions} \right) \\
& =\$20,000-\left(\$3,800+\$5,950\right)\\&=\$20,000-\$9,750\\&=\$10,250\end{align}\]
Now, calculate income tax by multiplying $8,700 with 10% tax rate and excess of $8,700 with 15%.
\[\begin{align}
& \text{Income}\,\text{tax}=\frac{10}{100}\times \$8,700+\frac{15}{100}\times\left(\$10,250-\$8,700\right)\\&=0.10\times\$8,700+0.15\times\$1,550\\&=\$870+\$232.5\\&=\$1,102.50\end{align}\]
(c)
In order to calculate the percent of federal taxes, divide the sum of FICA taxes and income tax with gross income and multiply by 100.
\[\begin{align}
& \text{Percent}\,\text{federal}\,\text{taxes}=\frac{\text{FICA}\,\text{taxes}+\text{Income}\,\text{tax}}{\text{Gross}\,\text{income}} \\
& =\frac{\$1,130+\$1,102.50}{\$20,000}\\&=\frac{\$2,232.50}{\$20,000}\\&=0.111625\end{align}\]
\[\begin{align}
& =0.111625\times 100 \\
& =11.1625\approx 11.2 \\
\end{align}\]
