After john worked at a job for 10 years, his salary doubled. if he started at $x, his salary after 10 years is $

If he started at $x, and we need to double it, we take X and multiply it by 2 creating $2X

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