Estimate the level of production which minimizes the cost

Question

Suppose the cost, in dollars, of producing x items is C(x) = 100x + 2000/x Determine

(a) the cost of producing 50 items,

(b) the cost of producing the 50th item, the marginal cost when x = 5,

(c) the average cost function,

(d) the average cost of producing 50 items,

(e) estimate the level of production which minimizes the cost and estimate the minimum cost.