Cow-herd
Algebra
Level
3
Four black cows and three brown cows give as much milk in five days as three black cows and five brown cows give in four days.
So which cow is the better milker?
Cannot be determined
Brown
Black
Both are efficient equally
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Let x and y be the amount of milk given by a black and brown cow respectively in a day.
5 ( 4 x + 3 y ) = 4 ( 3 x + 5 y ) 2 0 x + 1 5 y = 1 2 x + 2 0 y 8 x = 5 y ⇒ y = 5 8 x .
Hence the brown cow is more milky than the black cow.