During a snowmelt event, $2$ cfs $(\_3$

$/$sec$)$ of runoff containing salt at $250$ mg$/$L concentraGon is

flowing into a stream having an upstream flow of $10$ cfs and salt concentraGon of $15$ mg$/$L$.$

Assume that mass is conserved and there is complete mixing of runoff and in$-$stream water by the

Gme it reaches the outlet of the watershed. What is the concentraGon at the outlet? How many

pounds of salt per hour are flowing out of the watershed $?$