Question 20245
Let A equal the number of gallons pumped from well A in one minute to satisfy the conditions of the problem.

Let B equal the number of gallons pumped from well B in one minute to satisfy the conditions of the problem.

I need to pump 2400 Gallons per minute total flow from both wells.

A + B = gallons pumped from both wells in one minute, combining the first two conditions

A + B = 2400, combining all three conditions

change ppb to k / gal or kpg 

 A(18 kpg) + B(3 kpg) = 2400(5 kpg) 

 A(18 kpg) + (2400 - A)(3 kpg) = 12000 kpg

the units, kpg, all cancel  

 15A + 7200 -3A = 12000 

 12A = 4800 

A = 400 gal/min

B = 2000 gal/min