How can I run this problem in Matlab?

2.3.4. Mixing problems. In this final application we consider a mixing tank with an inflow of Q(t) gallons per minute and an equal outflow, where t is the time; see Fig. 7. The inflow is at a constant concentration ci of a particular solute (pounds per gallon), and the tank is constantly stirred, so that the concentration c(t) within the tank is uniform. Hence, the outflow is at concentration c(t). Let v denote the volume within the tank, in gallons; v is a constant because the inflow and outflow rates are equal. To keep track of the instantaneous mass of solute r(t) within the tank, let us carry out a mass balance for the "control volume" V (dashed lines in the figure): Rate of increase of mass of solute within V Rate in Rate out, (28) = - dx lb lb min (gal) QBal ct (29) min ga or, since c(t) = z(t)/u, da(t) + Q(t)x(t) = ciQ(t), dt (30)