(2) For this problem, assume that R(x) and C(a) represent the revenue and cost associ- ated to selling or making a units of a good. (a) (1 point) Using the general equation P(x) = R(x) - C(r), demonstrate that P'(a) = 0 exactly when R'(a) = C'(a). (b) (2 points) Explain in a sentence or two why your conclusion in part (a) makes sense (hint: as we discussed in class, think about P'(@), R'(o), and O(a) as the approximated profit/revenue/cost of the a + 1" unit)