Mathias Corporation manufactures and sells wire rakes. The rakes sell for $20 each. Information about the company's costs is as follows: Variable manufacturing cost per unit $9 Variable selling and administrative cost per unit $4 Fixed manufacturing overhead per month Fixed selling and administrative cost per month 350,000 a. Determine the company's monthly break-even point in units. b. Determine the sales volume (in dollars) required for a monthly operating income of $100,000. c. Estimate the amount by which monthly operating income will increase if the company anticipates a $200,000 increase in monthly sales volume