Answer:
20%
Explanation:
If the ratio of water to lemon juice is 4:1, that means that for every 5 portions of the cordial drink, 4 are water and 1 is lemon juice. In other words, 4/5 of the drink is water and 1/5 is lemon juice. The percentage of the lemon juice would be 1/5 = 20%. The answer is 20%.