Please explain how the circled part was taken. The data is below

There are two equally likely states of nature that can occur at date t + 1, either there is in an expansion or there is a recession. An investor has preferences over consumption at dates t and t + 1 that can be represented by the utility function U (Ct, C+1) = + BEP C+ +1 where y # 1 and B E (0, 1). The investor chooses her consumption plan to maximise U(Ct, Ct+1) taking prices of the financial assets as given. Let p; and pi denote the price of a bond and a share of the firm in period t, respectively. A risk-free bond issued at date t is a promise to pay 1 unit at date t + 1. The payoff of a share at date t + 1 is pit, + di1. The growth rate of consumption takes values gy in an expansion and gz in a recession, and the investor does not face any binding borrowing constraint.(a) Let c be the investor's optimal consumption plan. Since the investor does not face a binding constraint, she can freely buy or sell a marginal amount of the payoff It+ 1 at a price p. Then, she could have altered her consumption plan as follows: C1 = G - PL . Et If c maximises the investor's utility, then & = 0 is an interior solution to max U(Ct - Pt . g, at+1 + It+1 . {) Et and so the following FOC holds: Pt . Cil = B . EP CMH . It+1 I. . Pr = B . EP. Ci,t+ 1 . It+l It (1) Ci,t where miti = B. att Ci.t is agent i's sdf