[tex]\begin{gathered} \text{ratio 5:10} \\ \text{isabelle has 55 then} \\ \frac{55}{5}=11 \end{gathered}[/tex][tex]\begin{gathered} In\text{ order to conserve the ratio, it must ocurr that} \\ \text{Shane has 10}\cdot11=110 \\ \text{why? because} \\ \frac{110}{10}=\frac{55}{5}=11 \end{gathered}[/tex][tex]\text{Together Isabelle and Shane have 110+55=165}[/tex]