Required information

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Data for Hermann Corporation are shown below:

Per UnitPercent of SalesSelling price$135100%Variable expenses8160Contribution margin$5440%

Fixed expenses are $87,000 per month and the company is selling 2,900 units per month.

Required:

1-a. How much will net operating income increase (decrease) per month if the monthly advertising budget increases by $9,200 and monthly sales increase by $20,250?