Divide 15 into two parts such that product of square of one part and cube of other is maximum

Divide 20 into two parts such that the product of one part and the cube of the other is maximum. The two parts are

Divide 20 into two parts such that the product of one part and the cube of the other is maximum. The two parts are

Divide 5 into two parts such that the product of the square of one and the cube of the other may be the greatest possible.

Divide the number 84 into two parts such that the product of one part and the square of other is maximum.

Divide 20 into two parts such that the product of one part and the cube of the other part is maximum.

What is the product of two parts of 20 such that the product of one part and the cube of the other is maximum?