I just need help with question C

the answers I got for:

Question A = 200

Question B = 156

Starfall Bookstore orders and sells one of its magazines, Surprise Star magazine. It makes the following estimates for a vearlv period: The following table shows estimates of uncertainty experienced by Starfall Bookstore management when facing the various demand possibilities: Required: Calculate (a) the reorder point (3 Marks), (b) the optimal level of safety stock (6 Marks), and (c) the total costs associated with the optimal level of safety stock (6 Marks)