(* Calculating Firm Marginal Costs *)

<<Merger`



profits = (Array[p, n] - Array[c, n])q

rules = Flatten[{

        Table[a[i] -> aa[[i]], {i, n}],

        Table[p[i] -> p0[[i]], {i, n}], c[n] -> 0}];



eqns = Table[D[profits[[i]], p[i]], {i, n - 1}] /. rules

startingValues = Table[{c[i], p0[[i]]}, {i, 1, n - 1}]



FindRoot @@ FlattenAt[{eqns, startingValues, MaxIterations -> 500}, {2}]

NumberForm[TableForm[Transpose[{

        {"firm", FirmNames}, {"price", p0},

        {"choice prob.", q00}, {"marginal cost", 

          cc = MarginalCosts[aa, b, p0, q00]}}]], 3]