As a musician, Mary plans to use JC Music Co.'s service for recording drum sound in her songs. She can use either drum machines or drummers, and they can substitute three drummers with one drum machine. The cost of hiring a drummer is $8 per hour and the rental cost of a drum machine is $12 per hour. To minimize the cost of recording 120 songs (q = 120), how many drummers (L) and drum machines (K) should she use?