Three Robots Eject Water

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Three robots, Q, R, and L, which eject water independently and simultaneously, each at a characteristic, constant rate, can fill a pool in 10 minutes. How long does it take Robot Q, working alone at its constant rate, to fill that pool with water?

(1) Machines R and L can fill the pool in 20 minutes.

(2) Machines Q and L can fill the pool in 15 minutes.