Need help with understanding how to solve the 2nd question

19) Zaccaria Corporation has provided the following contribution format income statement. 19) Sales (5,000 units) Variable expenses Contribution margin Fixed expenses Net operating income $300,000 240,000 60,000 58,800 $1,200 If sales increase to 5,040 units, what would be the estimated increase in net operating income? Lob,p00 If the selling price increases by $4 per unit and the sales volume decreases by 400 units, what would be the estimated net operating income