A tank contains 150 gal of water and 75 oz of salt. Water containing a salt concentration of (1+ | sin t) oz/gal flows into the tank at a rate of 1.5 gal/min, and the mixture in the tank flows out at the same rate. (a) Find the amount of salt in the tank at any time. (b) Plot the solution for a time period long enough so that you see the ultimate behavior of the graph. (c) 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?