A truck is carrying orange juice, cherry juice, and pineapple juice bottles in a ratio of 1 : 3 : 7. If there are 39 cherry juice bottles, then how many pineapple juice bottles are there?

The 1:3:7 ratios mean that for each bottle of orange juice there are 3 bottles of cherry juice and 7 bottles of pineapple juice.

In particular, you can see that the number of bottles of cherry juice is three times the number of bottles of orange juice. So, if you divide the number of bottles of cherry juice by 3, you'll get the number of number of bottles of orange juice.

Then, you multiply the number of bottles of orange juice by 7 and you'll get the number of bottles of pineapple juice.

91

Step-by-step explanation:

3 x 13 = 39

7 x 13 = 91