The total cost function of the firm producing the two commodities x and y is given by C(x,y)= x-0.5xy + y. If x = 100

The total cost function of the firm producing the two commodities x and y is given by C(x,y)= x²-0.5xy + y². If x = 100 at first, y = 60, how much additional cost will the firm incur if the output of x increases by 3 units?