Fine Parisian Wine

Two wine merchants enter Paris, one of them with 64 casks of wine, the other with 20. Since they do not have enough money to pay the custom duties, the first pays 5 casks of wine and 40 francs, and the second pays 2 casks of wine and receives 40 francs in change. What is the price of each cask of wine and the duty on it?

Le Triparty en la science des nombres, Nicolas Chuquet, 1484

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