The total cost (in dollars) of producing $x$ golf clubs per day is given by the formula $$C(x) = 450 + 110 x - 0.2 x^2.$$

(A) Find the marginal cost at a production level of $x$ golf clubs.
$C'(x)$ =

(B) Find the marginal cost of producing 50 golf clubs.
Marginal cost for 50 clubs =