Why do cars with 6 inch exhausts sound so loud

That’s what i got when i looked up what the solutions were

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

C+19÷-17=17c+(-1.11764706)=17c=.11764706)c=18.1176471