Cow, Buffalo & Goat - Puzzle

Cow gives 2 Liters of Milk.
Buffalo gives 5 Liters of milk.
Goat gives 250 ml of milk.
The total milk required by a cattler is 40 Liters.
The cattler must keep 20 animals of all the three types.

Can you help the cattler decide what number of each animals must he keep to satisfy his needs?

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