6. Halley Company produces 1,400 parts each year that are used in one of its products. The unit product cost of this part is: Variable manufacturing cost Fixed manufacturing cost Unit product cost $ 9.10 4.20 13.30 The part can be purchased from an outside supplier for $9.40 per unit. If the part is purchased from the outside supplier, two-thirds of the fixed manufacturing costs can be eliminated. The effect on net operating income as a result of purchasing the part would be a: $5,460 increase $5,500 decrease. $1,500 decrease. $3,500 increase