A juice maker is experimenting with fruit blends. They find that 6 ounces of strawberry juice can be extracted from 2 cups of strawberries, and 21 ounces of blueberry juice can be extracted from 3 cups of blueberries. They prepare a blend using an equal number of cups of strawberries and blueberries. What percentage of this blend is strawberry juice?
30
40
50
60
70
