In order to find the total amount of miles Olivia rode in the two days, we just need to add the mixed numbers that represent the amount rode in each day.
So we have:
[tex]\begin{gathered} 3\frac{1}{2}+1\frac{1}{4} \\ =(3+\frac{1}{2})+(1+\frac{1}{4}) \\ =(3+1)+(\frac{1}{2}+\frac{1}{4}) \\ =(4)+(\frac{2\cdot1+1}{4}) \\ =4+\frac{3}{4} \\ =4\frac{3}{4} \end{gathered}[/tex]So Olivia rode 4 3/4 miles (that is, 4.75 miles) in the two days.