is this correct?

The Chimes Clock Company sells a particular clock for $70. The variable costs are $21 per clock and the breakeven point is 270 clocks. The company expects to sell 320 clocks this year. If the company actually sells 370 clocks, what effect would the sale of additional 50 clocks have on operating income? Explain your answer. The sale of an additional 50 clocks would the additional contribution margin. increase operating income by the amount of The total effect would amount to 2450