-ast month when Holiday Creations, Incorporated, sold 39,000 units, total sales were $156,000, total variable expenses were $121,680, and fixed expenses were $36,200. Required: What is the company's contribution margin (CM) ratio? 2. What is the estimated change in the company's net operating income if it can increase sales volume by 400 units and total sales by $1,600 ? (Do not round intermediate calculations.)