Answer: Damon used 4 cups of lemon juice.
Explanation:
Given : The total number of cups in lemonade by mixing lemon juice and water. = 20 cups
Also, it is given that ,
Ratio of cups of lemon juice and water in one lemonade by the tape diagram = 1 lemon juice and 4 water
⇒ The ratio of cups of lemon juice and water in one lemonade = 1 : 4
Let the 'a' denotes the number of cups of lemon juice in one lemonade.
Then, The number of cups of water in one lemonade = 4a
According to the question , we have

Hence, Damon used 4 cups of lemon juice.