A $10$x$10*$ m$\text{'}$ Lake has been receiving flow of a BOD at a rate of $5$ m$\%$ and concentration of

$10$ mg$/$L$.$ There is also industrial outfall into the lake that discharges BOD at a rate of $0,5$ m$/$s and concentration ef $100$ mg$/$L$.$ The BOD has decay rate of $0\mathrm{.}2$ per day. Assuming completely mixed and steady state conditions. What would be the concentration in the in the lake after $7)$ days late.$)$