Let C(x) = 11x + 7 be the cost (in hundreds of dollars) to
produce x units of a certain commodity, and the R(x) = ?x^2 + 19x
be the revenue (in hundreds of dollars) from the sale of x units of
that commodity. How many units must the manufacturer of the
commodity produce and sell in order to maximize their profit? What
is that maximum profit? Note that profit can be computed by
subtracting cost from revenue.