$28\mathrm{.}4$ If $c_{in}=c_b(1-e^{-0\mathrm{.}12t}),$ calculate the outflow concentration of a conservative substance $($no reaction$)$ for a single, completely mixed reactor as a function of time. Use Heun's method $($without iteration$)$ to perform the computation. Employ values of $c_b=40m\frac{g}{m^3},Q=6\frac{m^3}{m}in,V=100m^3,$ and $c_0=20m\frac{g}{m^3}.$ Perform the computation from $t=0$ to $100$ min using $h=2.$ Plot your results along with the inflow concentration versus time.