the cost to produce x thousand automobiles is given by the function
c(x)=4x^2-8x+3. the price that we charge is p(x)=16-2x. what is the
revenue? what is the profit for producing x thousand automobiles? what
is the number of automobiles that must be produced to maximize profit?
must show all work.

Set marginal revenue equal to marginal cost.
To find marginal revenue, get total revenue (price times quantity) and
differentiate it.
Differentiate cost to get marginal cost.  
Set MC=MR and solve for x.