what am I doing wrong it said to remove x and replace it with 100% sodium chloride

41-gallon barrel contains a mixture with a concentration of 33% sodium chloride. You remove x gallons of this mixture and replace it with 100% sodium chloride. (a) Write the amount A of sodium chloride in the final mixture as a function of x. A ( x ) = 13.53 - 33 100 X (b) Use a graphing utility to graph the concentration function. What is the domain of the function? (Enter your answer using interval notation.) (c) Approximate (accurate to one decimal place) the value of x when the final mixture is 60% sodium chloride. X = gal