I’m stuck on this one..can someone help? (It’s a quiz)

Answer:
This have a lot of solutions. Include x=5 y=1, x=7 y=2, x=9 y=3 and so on...
Step-by-step explanation:
Their are two things we don't know (x and y).
We need two effective message, and the first and the second formula are same, so we can't find only one answer.