To find the cost per bag of lemons, you can divide the total cost by the number of bags.
The total cost is $19.75 for 5 bags, so the equation is:
\[ c = \frac{19.75}{5} \]
Now, calculating that gives:
\[ c = 3.95 \]
So the complete equation is:
\[ c = \frac{19.75}{5} \quad \text{or} \quad c = 3.95 \]