Let V be the number of containers of vanilla ice cream that Manny uses, and P be the number of peach ice cream containers that Manny needs to obtain 11 containers at a cost of $8 each. Then we can set the following system of equations:
![\begin{gathered} V+P=11, \\ 6V+11.5P=11\cdot8. \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/by8aj601mjvqit4cxupnvm0l4nlro1bwc4.png)
Solving the first equation for V we get:
![\begin{gathered} V+P-P=11-P, \\ V=11-P\text{.} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/b49tdu0e30cskaypjfzqlcmr3l5yt8a5es.png)
Substituting the above equation in the first one we get:
![6(11-P)+11.5P=11\cdot8.](https://img.qammunity.org/2023/formulas/mathematics/college/4n8d4ugf4m0jnsmmzinwsh0pkuk0rhol1d.png)
Simplifying the above equation we get:
![\begin{gathered} 66-6P+11.5P=88, \\ 66+5.5P=88. \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/zdki2hn2xams5e8r2sucvx3bfozjpx49bj.png)
Subtracting 66 from the above equation we get:
![\begin{gathered} 66+5.5P-66=88-66, \\ 5.5P=22. \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/7dqcq13869m29tjg4cjwi3znojlky0qmlu.png)
Dividing the above equation by 5.5 we get:
![\begin{gathered} (5.5P)/(5.5)=(22)/(5.5), \\ P=4. \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/erujsg1k781q0fysuxkziv8kuhc27efqv9.png)
Finally, substituting P=4 in V=11-P we get:
![\begin{gathered} V=11-4, \\ V=7. \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/evzrm4aqr7d8vfc8s4xljogyirpmh7y2jc.png)
Answer: Manny needs 7 containers of vanilla ice cream and 4 containers of peach ice cream.