Urgent: Inventory Model. Solve step by step. thanks

Question:

Consider an item with the following deterministic, time-varying demand pattern:

Week 1 2 3 4 5 6 7 8 9 10 11 12

Demand 50 80 180 80 0 0 180 150 10 100 180 130

Suppose that the pattern terminates at week 12. Let other relevant characteristics of the item be:

Inventory carrying cost per week is $0.20/unit

Fixed cost per replenishment (order cost) is $30

Initial inventory and replenishment lead time are both zero.

Determine optimal ordering policy and total relevant costs using:

a) Wagner-Within method