An electric water heater held at 140 degrees F is kept in a 70 degree F room...

An electric water heater held at 140 degrees F is kept in a 70 degree F room.  When purchased, its insulation is equivalent to R 5.  An owner puts 25-ft^2 blanket on the water heater, raising its total R value to 15.  Assuming 100% conversion of electricity into heated water, how much energy (kWhr) will be saved each year? if electricity costs 8.0 cents/ kWhr, how much money will be saved in energy each year?

I believe its  q=A(T2-T1)/R, but  don't know the area

One day, you are out hiking and find a beautiful river where you want to go fishing.  The river is flowing at 1.5m/s.  Next to the river, there is an abandoned mine leaching copper in the river at a concentration of 14mg/L.  Copper is toxic to fish at concentrations above 1.0mg/L.  Fortunately, copper precipitates out of the water as river flows downstream,  which can be considered second order decay, with k=1.2Lmg-min.
If you are downstream 50 meters from the mine, will the copper concentration be below the toxic level, so that you can go fishing?  Model the river as a plug flow reactor and assume that steady state conditions apply

I believe its 2nd order so -kc^2=1/Con.out=1/Con.in+kt