Please derive a quadratic transfer function that gives me the composition and height.It is desired to control the composition and the level of the mixing tank used to prepare a saline solution

at the nominal value by two PID controllers. There are $2$ inlet streams entering the mixing tank. Density

of the mixture can be assumed constant through out the mixing process. The dilute inlet stream has a

constant composition of $10wt\%$ with a nominal flowrate of $5k\frac{g}{m}in.$ The other concentrated stream

has a constant composition which is $80\%$ and has a nominal stream flowrate of $4k\frac{g}{m}in.$ It is desired

to keep the level of the cylindrical mixing tank with a crosssectional area of $1m^2$ at $3m.$