Examples of this are:
2 and 
2 and 
4 and 
I'm guessing you have a work sheet going along with this which has actual images of containers. I've attached an example - if you can post the actual work sheet you're referring to I can edit this answer to correctly reflect your specific question.
Answer: 1/3
Step-by-step explanation:
Answer:
the answer to the questions are x, 4 and y=7
2 adults = 5.50 x 2 = 11
3 students = 4.25 x 3 = 12.75
Total = $23.75