[Sum Formula & Recurrence Formula] Algorithm Efficiency

I have attached the Knapsack Algorithm and its recursive worst case cost I_n (Picture below for both)

1 a) Use iteration to find a formula for In which involves a sum

1 b) Solve the recurrence relation (i.e find an analytical formula for I_n)

knapsack(W.Vitk) W is set of weights of all items Vis the set of values of all items i is the item number k is the capacity of the knapsack to solve if i -0 then return 0 elseif k-W[i] w cost i, w j max( cost i -1, w j, costl i 1, w Wil) if, Wik- w knapsack(W.Vitk) W is set of weights of all items Vis the set of values of all items i is the item number k is the capacity of the knapsack to solve if i -0 then return 0 elseif k-W[i] w cost i, w j max( cost i -1, w j, costl i 1, w Wil) if, Wik- w