Bob Dylan

The monthly revenue achieved by selling x wristwatches is figured to be x(40-0.2x)dollars. The wholesale cost of each watch is $32. a. How many watches need to be sold each month to achieve a profit (revenue-cost) of $50? for this part I did x(40-.2x)-32x...

How do you know that it is supposed to have an a in front?

Perhaps for b you do the vertex -b/2a? but I get 30 is that right?

I can't understand how part a. could be either 8 or 32. How could it be more than one answer?

36