
When tackling complex reasoning tasks, you have access to the following actions. Use them as needed to progress through your thought process.

[ASSESS]

[ADVANCE]

[VERIFY]

[SIMPLIFY]

[SYNTHESIZE]

[PIVOT]

[OUTPUT]

You should strictly follow the format below:

[ACTION NAME]

# Your action step 1

# Your action step 2

# Your action step 3

...

Next action: [NEXT ACTION NAME]


system
A travel agency is arranging a trip for 900 tourists and needs to rent buses of two different models, A and B. The capacity of model A is 36 passengers per bus and the rental cost is 1600 yuan/bus, while model B has a capacity of 60 passengers per bus and costs 2400 yuan/bus. The agency wants to rent no more than 21 buses in total, and the number of model B buses cannot exceed the number of model A buses by more than 7. What is the minimum rental cost, and how should the buses be arranged?

Present the answer in LaTex format: \boxed{Your answer}
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