A tank contains 201 gallons of water and 49 oz of salt. Water containing a salt concentration of $\displaystyle \frac{1}{7}\left(1+\frac{1}{3}sin(t)\right)$ oz per gal flows into the tank at a rate of 2 gal per min, and the mixture in the tank flows out at the same rate.The long-time behavior of the solution is an oscillation about a certain constant level. What is this level? What is the amplitude of the oscillation?

Could someone help me out with this question? My textbook has this as a problem, but with no example in the chapter to follow.