Contribution margin

A tile manufacturer has supplied the following data:
Boxes of tile produced and sold 625,000
Sales revenue $2,975,000
Variable manufacturing expense $1,720,000
Fixed manufacturing expense $790,000
Variable selling and admin expense $152,000
Fixed selling and admin expense $133,000
Net operating income $180,000
Required:
a. Calculate the company's unit contribution margin
b. Calculate the company's unit contribution ratio
c. If the company increases its unit sales volume by 5% without increasing its fixed expenses, what would the company's net operating income be?