The stor buys the pencils for 0.20 and sells them for 0.25.
The difference between these two values represents the profit per pencil:
0.25-0.20= 0.05
The store profits 0.05cents per pecil sold.
One dozen equals 12 pencils, multiply it by 5 to know how many pencils are in 5 dozens:
12*5=60
The store sold 5 dozen pencils, this means they sold 60 pencils.
Multiply the profit per pencil by the total number of pencils sold to get how much they made:
60*0.05=3
For the 5 dozen pencils sold, the store made $3 profit.