need help calculating with the following practice problem , thank you very much .

Exercise 5-1 The Effect of Changes in Activity on Net Operating Income (L05-11 Whirly Corporation's contribution format income statement for the most recent month is shown below: Sales (7,400 units) Variable expenses Contribution margin Fixed expenses Net operating income Total $ 244,200 148,000 96,200 55,709 $ 40,500 Per Unit $ 33.00 20.ee $ 13.00 Required: (Consider each case independently): 1. What would be the revised net operating Income per month if the sales volume increases by 90 units? 2. What would be the revised net operating Income per month if the sales volume decreases by 90 units 3. What would be the revised net operating income per month if the sales volume is 6 400 units? 1 Revised not operating income 2 Revised not operating income 3 Revised not operating income