A company manufactures x units of one item and y units of another. The total cost in dollars, C, of producing these two items is approximated by the function C=4x^2+3xy+6y^2+600.
(a) If the production quota for the total number of items (both types combined) is 154, find the minimum production cost.
cost = 74289 (CORRECT ANSWER)
(b) Estimate the additional production cost or savings if the production quota is raised to 155 or lowered to 153.
production cost or savings = __________ (MISSING ANSWER)