Titanium Products, a manufacturer of aircraft landing gear, makes 1,000 units each year of a special valve used in assembling one of its products. The unit cost of producing this valve includes variable costs of $70 and fixed costs of $60. The valves could be purchased from an outside supplier at $77 each. If the valve were purchased from the outside supplier, 40% of the total fixed costs incurred in producing this valve could be eliminated. Buying the valves from the outside supplier instead of making them would cause the company's operating income to:

I have the answer: Increase by $17,000. I'm looking for the math on how to get there.

Thank you!