[tex]2\frac{3}{10} +2\frac{3}{10} =\frac{(2\times10)+3}{10}+\frac{(2\times10)+3}{10} =\frac{20+3}{10}+\frac{20+3}{10}\\\\=\frac{23}{10} +\frac{23}{10} =\frac{23+23}{10} =\frac{46}{10} =4\frac{6}{10} =\boxed{\bf{4\frac{3}{5}}}[/tex]
Marissa rode 4 3/5 miles in all.