Q: During a certain soccer tournament, a guy sells the jerseys of some teams. The selling price of the jersey are:

Brazil:$170, England:$104, Argentina:$130, Italy:$78

If the total revenue is $3600, how many jerseys of Brazil has sold?

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Have no idea where to start with.

I would really like to take on the question myself, please do give hints instead of the answer, if possible.

Thanks.