If neither restaurant cleans, each will earn $12,000; alternatively, if they both hire workers to clean, each will earn only $9,000. however, if one cleans and the other doesn't, more customers will choose the cleaner restaurant; the cleaner restaurant will make $16,000, and the other restaurant will make only $4,000.

The best option for both restaurants is not to clean.

Explanation:

If they both do not clean and they can agree on not doing it, they total income for both would be $24,000 a month, if they do clean the total income would be $18,000 and if one does and the other do not, it would be $20,000 the best option for total income of both of them would be to not clean and each earn $12,000.

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