Answer:
cups of strawberry she used = 15 cups
Explanation:
Karena makes berry sauce using a ratio of 2 cups blueberry sauce to 5 cups strawberry sauce. The ratio of blueberry sauce to strawberry sauce is 2:5. From the ratio the total berry sauce will be 7. That is the ratio of strawberry sauce to the berry sauce = 5:7 which is 5/7 and the ratio of blueberry sauce to the berry sauce is 2:7 which is 2/7.
Since she makes 21 cups of berry sauce the number of strawberry cups she uses can be calculated as follows
Ratio of cups of strawberry sauce to cups of berry sauce = 5/7
She makes 21 cups of berry, therefore,
cups of strawberry she used = 5/7 × 21
cups of strawberry she used = 5 × 3
cups of strawberry she used = 15 cups