Answer
$12.32$ minutes.
Work Step by Step
Aaron loads $\displaystyle \frac{1}{22} $ of the van in one minute.
Elizabeth loads $\displaystyle \frac{1}{28} $ of the van in one minute
Together, in one minute, they load
$\displaystyle \frac{1}{22}+\frac{1}{28}=\frac{28+22}{22\cdot 28}=\frac{25}{308}$ of the van.
It will take them $\displaystyle \frac{308}{25}=12.32$ minutes to load the van.
