Data for Hermann Corporation are shown below: Fixed expenses are $76,000 per month and the company is selling 2.500 units per month. Required: a. The marketing manager argues that a $8, 100 increase in the monthly advertising budget would increase monthly sales by $15, 500. Calculate the increase or decrease in net operating income. b. Refer to the original data. Management is considering using higher-quality components that would increase the variable expense by $4 per unit. The marketing manager believes that the higher-quality product would increase sales by 20% per month. Calculate the change in total contribution margin.