The Sterling Tire Company's income statement for 2015 is as follows:

STERLING TIRE COMPANY
Income Statement
Year ended December 31, 2015
Sales (20,000 tires at $60 each) .....................$1,200,000
Less: Variable costs (20,000 tires at $30)............600,000
Contri bution marg in ........................ . .................600,000
Less: Fixed costs ....................... .. . .....................400,000
Earnings before interest and taxes (EBIT).............200,000
Interest expense ............................ ........................50,000
Earnings before taxes (EST)..................................150,000
Income tax expense (34%) ... .. ......... .. .. . ............51,000
Earnings after taxes (EAT) ..................................$ 99,000

Given this income statement, compute the following:
a. Degree of operating leverage.
b. Degree of financial leverage.

c. Degree of combined leverage: Comment on the impact of a 20 percent increase in sales. Does financial or operating leverage have the greater impact?
d. Break-even point in units.
e. Break-even point considering the interest expense as a fixed cost.