The allegheny and monongahela rivers meet at pittsburgh to form the mighty ohio river. the allegheny, flowing through forests and small towns, runs at an average flow of 340 cubic feet per second (cfs) and has a low solid concentration of 130 mg/l. the monongahela, on the other hand, flows at 460 cubic feet per second (cfs) through old steel towns and farms, carrying a solids concentration of 500 mg/l. conduct a non-reactive mass balance to determine: a. what is the average flow (in cfs) in the ohio river? (10 points) b. what is the solids concentration (in mg/l) in the ohio river? (10 points) your solution must show the system around which mass balance is conducted, the system boundary, the mass balance equations and all assumptions made. show all work clearly.