To find the better buy we have to find the cost per pen for each.
1. 20 pens for $1.60 -> 1.60/20 = .08 cents per pen.
25 pens for $2.25 -> 2.25/25 = .09 cents per pen.
The best buy is 20 pens for $1.60 because it's cheaper per pen.
2. 13 berries for $2.60 -> 2.60/13 = .20 cents per berry
17 berries for $3.06 -> 3.06/17 = .18 cents per berry
The best buy is 17 berries for $3.06 because it's cheaper per berry.
