The function ​f(x)​ is the number of feet below the surface of the water a diver is at x seconds. It took the diver 20 seconds to swim a depth of 15 feet and return to the surface. What is the practical domain for the function f(x)?

So don't take my word i'm not exactly a mathematical person but i would assume a. because while selling the soap every month you increase in sells so you would by 11 percent. the you would get the factor 0.89 which if i had to guess would be the monthly profit over 11 probably wrong tho