To answer this question, you need to equalize the content of the cranberry for both solutions. The content could be count by multiplying the percentage with the volume of the cranberry juice. Then the calculation would be:
content1= content2
concentration1 * volume1= concentration2 * volume2
12%* 25 ml = 20%* volume2
volume2= 25ml * 12%/ 20%= 15ml
