To find the cost per bag of lemons, we can set up the equation based on the total cost for the 5 bags.
Let \( c \) represent the cost of each bag of lemons. Since Julio bought 5 bags for a total of $19.75, we can write the equation as:
\[ 5c = 19.75 \]
This equation models the total cost \( 19.75 \) in terms of the number of bags (5) and their cost per bag \( c \).