A political campaign manager negotiated radio & television time for a candidate’s political announcements. The budget is limited to $48,000 on the announcements. Each 60-second radio spot cost $200, whereas 30 seconds of television time costs $600. The manager wants at least 45 radio spots, but no more than 90 and at least 20 television spots. Is the following system of inequalities correct?

200 r +600 t ≤ 48000
45≤ r ≤ 90
t ≥ 20