Answer: 78 juice boxes
Explanation:
The Gregory family thinks that they will need 15 juice boxes for every 5 children.
The number of juice boxes they will need for every child is:
= Number of juice boxes for 5 children / 5
= 15 / 5
= 3 juice boxes per child
If they are expecting 26 children, they will need:
= 3 * 26
= 78 juice boxes