6. Return to the final example of section 5.5,in which the demand for AIDS drugs was Qn = 100 – Pin North America and Qs =a 100 – P in

Sub-Saharan Africa. Show that with marginal cost = 20 for such drugs, it must be the case that e > 0.531 if the drug manufacturer is to serve both markets while charging the same price in each market.(HINT: Calculate the total profit if it serves only North America and then calculate the total profit if it serves both markets. Then determine the value of a for which the profit from serving both markets is at least as large.)