Answer: 8 cups
Explanation:
Let the cups of orange juice concentrate that he used be represented by x.
Therefore, based on the information, we can form an equation which will be:
2/5 = x/20
Cross multiply
5 × x = 2 × 20
5x = 40
x = 40/5
x = 8
Therefore, he used 8 cups of orange juice concentrate.