A cran-apple juice recipe calls for 3 cups of cranberries to 5 cups of apples. You decide to make 15 cups of cran-apple juice. How many cups of cranberries and apples do you use?
a) 9 cups cranberries, 25 cups apples
b) 6 cups cranberries, 9 cups apples
c) 9 cups cranberries, 15 cups apples
d) 10 cups cranberries, 15 cups apples