The Lees, a family of two adults and two dependent children under age $16,$ had a gross annual income of $$72,000\mathrm{.}00$ for $2020.$ Determine their standard deduction and child tax credit amounts, as well as their marginal and average tax rates, assuming their filing status is married filing jointly. Why is their average tax rate lower than their marginal rate?

Assuming the Lees' filing status is married filing jointly spouse, their standard deduction for the $2020$ tax year is $$,($Enter the amount to the nearest cent.$)$ Click the following link for a standard deduction table: