Answer
Find out the percent increase in the price per cheese stick.
To prove
As given
Cheese sticks that were previously priced at "5 for $1" are now "4 for $1".
i.e previously the price of the 5 cheese stick is $1 .

= 0.2
Now the price of the 4 cheese stick is $1 .

= 0.25
Change in price per cheese stick = now price - previous price
= 0.05
Formula

Put all the value in the formula

= 25%
Therefore the percent increase in the price per cheese stick is 25%.