You buy a container of cat liter $13.75 and and a bag of cat food for x dollars. the total purchase is $20.80, which includes 4% sales tax. write and solve an equation to find out the cost of the car food

In this question it is important to note down all the important information's that are mentioned in the question.
Cost of a container of cat liter = $13.75
Cost of a bag of cat food = X dollars
Total amount of money required to purchase the items = $20.80
Percentage of sales tax that had to be given = 4%
Then
Amount of sales tax given = (4/100) * 20.8 dollars
                                           = 20.8/25 dollars
                                           = 0.83 dollars
Then the total purchase price for the two items = 20.80 - 0.83 dollars
                                                                            = 19.97 dollars
Now we can easily find the cost of the cat food by subtracting the cost of the liter from the total purchase amount.
Then
Cost of the cat food = 19.97 - 13.75 dollars
                                 = 6.22 dollars
So the cost of the bag of cat food is $6.22