A tank contains http://webwork.math.uwyo.edu/webwork...ba0c4005e1.png kg of salt and http://webwork.math.uwyo.edu/webwork...0f746f9fb1.png L of water. A solution of a concentration http://webwork.math.uwyo.edu/webwork...cbec96e741.png kg of salt per liter enters a tank at the rate http://webwork.math.uwyo.edu/webwork...fc95b6a081.png L/min. The solution is mixed and drains from the tank at the same rate.

Find the amount of salt in the tank after http://webwork.math.uwyo.edu/webwork...e94e38c1d1.png hours.

I got something like 36 kg and my equation was

A= (320e^(-8t/1000)-320)/-8

but i dont think this is correct