Felipe planted some seeds for a science project. One of his plants grew $\displaystyle{6}\frac{{3}}{{8}}\usepackage{cmbright}\Huge\$ inches in the first week, and then it grew $\displaystyle{5}\frac{{11}}{{16}}\usepackage{cmbright}\Huge\$ inches during the second week. How much did the plant grow during these two weeks?

The answer should be written as a proper mixed number and should be simplified, if possible.