Shannon:
$13.50/2 = $6.75
$20.25/3 = $6.75
Each of Shannon's shirts cost $6.75.
The difference in price per shirt is $7.50 - $6.75 = $0.75.
Anna:
c = 7.50n
For 1 shirt, n = 1, so
c = 7.50 * 1 = 7.50
Anna's shirts cost $7.50 each.
Answer: Shannon found the better buy because the shirts cost $0.75 less.