What are the primary variables influencing stroke volume (sv)? check all that apply. chronotropic agents afterload venous return or preload contractility or inotropic agents?

Data for hermann corporation are shown below: per unit percent of sales selling price $ 125 100 % variable expenses 80 64 contribution margin $ 45 36 % fixed expenses are $85,000 per month and the company is selling 2,700 units per month. required: 1-a. how much will net operating income increase (decrease) per month if the monthly advertising budget increases by $9,000 and monthly sales increase by $20,000? 1-b. should the advertising budget be increased?