Machine R, working alone at a constant rate, produces x units of a product in 30 minutes, and machine S, working alone at a constant rate, produces x units of the product in 48 minutes, where x is a positive integer.
Quantity A
The number of units of the product that machine R, working alone at its constant rate, produces in 3 hours
Quantity B
The number of units of the product that machine S, working alone at its constant rate, produces in 4 hours