A music company produces two types of digital keyboards, one is full-weighted and another is semi-weighted. Both keyboards are sold for $2800 and $2400 respectively. There are about 3500 oscillator chips available every day from which the full-weighted version requires 20 chips while the semi-weighted version requires 15 chips. The company has a total of 6 working hours a day. Both of these keyboards require a production time of 1.2 hours. What should be the manufacturing quantity for each of the keyboards to maximize the total revenue?