Separable Differential Equations: Videos & Practice Problems

A $2,000,000$-$\text{L}$ reservoir is polluted with a chemical at a concentration of $25\text{ g/L}$. Clean water flows in at $2,500\text{ L/hr}$, and the mixture is drained at the same rate. How long will it take for the concentration to fall to $20\%$ of its initial value? Round the answer to the nearest whole number.