A small manufacturing plant produces two kinds of bicycles—single speed and ten-speed. The plant can manufacture up to 400 of the single speed bicycles and up to 500 of the ten-speed bicycles per month, but it can only manufacture a total of 650 of both kinds every month. It takes 40 man-hours to manufacture a single-speed bicycle and 80 man-hours for the ten-speed; there are 44,000 man-hours available per month. The profit on a single-speed bicycle is $20 and the profit on a ten-speed bicycle is $30.

Determine the production schedule that will maximize the total monthly profit z from the manufacture and sale of x single speed and y ten-speed bicycles.