Y varies directly as x. find k when x is 12 and y is 45.

The maximum number of bacteria supportable by a particular environment is 900,000 and the rate of bacterial growth is jointly proportional to the number present and the difference between 900,000 and the number upresent. determine the number of bacteria present when the rate of growth is maximum.hint: let f(x) bacteria per minute be the rate of growth when there are x bacteria present​