Judging from part E, the total volume in each tank is supposed to be constant. Neither the original data nor the modified data achieve that.
I suggest you put in unknowns for the rate of flow from outside the system into tank1 and the rate of return from tank2 to tank1. The other two flow rates can then be deduced. solve the question in terms of those unknowns. When you get the right data, you can just plug it in to your equations.