A firm is planning to spend $75,000 on advertising. It costs $3000 per minute to advertise on television and $1000 per minute to advertise on radio. If the firm buys x minutes of television...

A firm is planning to spend $75,000 on advertising. It costs $3000 per minute to advertise on television and $1000 per minute to advertise on radio. If the firm buys x minutes of television advertising and y minutes of radio advertising, its revenue in thousands of dollars is given by -0.3x²
- 0.4y²
+ 0.8xy + 5x + 10y. How can the firm maximize its revenue?