The function describing this graph is a transformation of the parent cosine function, y = cos x.
which value best describes the amplitude of the transformed function?

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

I  dont  know much about vertexes but i know to solve this function you need to use foil method and then corresponmd the vertex with the actual coordinates, hope i !