To solve this you need to calculate the cost per milliliter of both juices. 355ml costs 1.25. So if you divide the 1.25 by 355ml you will get the cost of 1 ml The second you will have to convert L to ml by multiplying the L by 1000 (move decimal 3 places right) use this value to calculate same as before. find the difference between the two 1ml values to calculate your savings.