Guelph Manufacturing produces metal picture frames. The company's income statements for the last two years are presented below: Last Year This Year Units Sold 60,000 80,000 Sales $850,000 $1,200,000 Less: Cost of goods sold 600,000 750,000 Gross margin 250,000 450,000 Less: Operating expenses 150.000 180.000 Net income $100,000 $270,000 The company has no beginning or ending inventories. Required: a. Estimate the company's total variable cost per unit, and its total fixed costs per year. (Remember that this is a manufacturing firm.) b. Compute the company's contribution margin for this year