The production function is f(L,M)=4L1/2M1/2, where L is the number of units of labor and M is the number of machines. If the amounts of both factors can be varied

and if the cost of labor is $64 per unit and the cost of using machines is $1 per machine, then the number of machines needed toproduce 64 units of output is

Group of answer choices

128

2

80

40

5/8