A freight elevator is rated to lift up to 3,600 pounds total. On one trip, it must carry a 120-pound operator and only two types of cargo containers: small containers (each 30 pounds) and large containers (each 75 pounds). If $s$ is the number of small containers and $l$ is the number of large containers, which inequality models all possible combinations of $s$ and $l$ that can be carried at once?