A small firm produces both AM and AM/FM car radios. The AM radios take 15 hours to produce, and the AM/FM radios take 20 hours to produce. The number of production hours is limited to 300 hours per week. The plant's capacity is limited to a total of 18 radios per week, and existing orders require that at least 4 AM radios and at lease 3 AM/FM radios be produced per week. Write a system of inequalities representing this solution. In this case let x=AM radios and y= AM/FM radios.