Number of cars owned by Rita for rentage is 29,
Let C represent the number of cars left after renting R number of cars out,
Let the equation relating them be,
![29-R=C](https://img.qammunity.org/2023/formulas/mathematics/college/b6mvf3n15oz75xui30fk3kpaf20mqxd40q.png)
If she rents out 9 cars, then,
![\begin{gathered} R=9\text{ cars} \\ 29-R=C \\ C=29-R \\ C=29-9=20 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/lld9ad0fw7bidjroezuhpv5behx9d59n9e.png)
Hence, the number of cars she would have left, C, is 20 cars.