Here is the question

This is what I have completed so far. How do we get the cost per shirt. Please explain? I get the $1440 cost for good-quality sweatshirt. Where does 144 come from?

Jayne reminded Michael that maintenance of the machines is required for the silk-screen process. In addition, Michael realizes that he must consider the cost of utilities. The building Michael wants to rent is roughly the same size as the building occupied by Shirts and More. In addition, Shirts and More sells ap- proximately the same number of shirts Michael plans to sell in his store. There- fore, Michael is confident that the maintenance and utility costs for his shop will be comparable to the maintenance and utility costs for Shirts and More, which are as follows within the relevant range of zero to 8,000 shirts. Shirts Sold 2,000 2,110 2,630 3,150 5,000 5,300 3,920 2,080 8,000 6,810 6,000 3,000 Maintenance Costs $1,716 1,720 1,740 1,740 1,758 1,818 1,825 1,780 1,914 1,860 1,855 1,749 Utility Costs $1,100 1,158 1,171 1,198 1,268 1,274 1,205 January February March May Junc Ju August September Octobc November December 1,400 1,362 1,347 1,193 Michael estimates the number of shirts to be sold in the first five quarters beginning January 2013, to be: First quarter, year 1 Second quarter, year 1 Third quarter, year 1 Fourth quarter, year 1 First quarter, year 2 8,000 10,000 20,000 12,000 18,000