A dog food manufacturer wants to advertise its products. A magazine charges 60$ per ad and requires a min of three ads. A radio station chages 150$ per commercial minute and requires at least 4 min. Each magazine reaches 12,000 people while each commercial minute reaches 16,000 people. At most, 900$ dollors can be spent on advertising.

1. Let "a" represents magazine ads and "m" represent the number of comercial minutes. Write a system of inequalities that represent the advertising plan for the company.

2. How many ads and commercial minutes shlould be purchased to reach the most people? How many people would this be?

Having a problem for some reason with the first part of this for system of equalities and it is messin with my mind!!!

Help please.