Help with C please.

Use this income statement to answer the following questions. $6,000 4,200 1,800 Sales ($60 per unit) Less: Cost of goods sold ($42 per unit) Gross margin Less operating expenses: Salaries Advertising Shipping ($3 per unit) Operating Income $800 400 300 1,500 $300 By how much would operating income change with a 10% increase in units sold? (Round ans Operating Income $ $