(x^6z^9)(4xyz^9)(-5x^8y^6)

We can re arrange this:
(-5)*(4) * x^6 * x * x^8 * y * y^6 * z^9 * z^9

using exponent properties
we can get
-20 x^15 y^7 z^18
as our simplified answer.

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