Help me do these macroeconomics questions

(c) Use the solution to the firm maximization problem and the expression of P, to derive the formula (15). NOTE: In their original QJE paper, there are a couple of typos! In particular, (12) and (13) are not correct if MRPL, and MRPK, are defined as in their paper following (12) and (13). As a hint: define 1 M. 1 PAY si MRPL, 1= 1 MRPL,, PY. and MRPK, similarly. (d) There is a large literature trying to link the distortions (Ty,,, TK., ) to financial frictions individual firms face. To see the relation between these exogenous taxes and credit constraints, suppose that there are no taxes (i.e. Ty. = TK. = 0) but firm i faces a credit constraint of the form Whyi + (RKsi PHYSi i=1 subject to M. Y. = (2) Determine P.. (b) Let As be the multiplier on the constraint (2). Show that the profit maximization of firm i in industry s is max (1 - TY.. ) As (Ysi)- Whyi - (1 + TKsi) RK si Ysi, Lsi.K si subject to Ys; = A,; Ko. Ll-a