A 1000 L tank contains 500 L of water with a salt concentration of 10 g/L. Water with a salt concentration of 65 g/L flows into the tank at a rate of 80 L/min. The fluid mixes instantaneously and is pumped out at a specified rate Rout . Let y(t) denote the quantity of salt in the tank at time t. Find the salt concentration when the tank overflows assuming that Rout = 40 L/min. (Use decimal notation. Give your answer to one decimal place.) the concentration of salt: g/L