Answer:
(13 + Y) / 5
Explanation:
What we must do is calculate the total number of jewels and divide by the number of sisters, so we will know the amount each receives.
We know that originally there are 13 jewels, but it also gives "Y" jewels, therefore the total jewels would be:
13 + Y
Now, to know how much each one receives it would be:
(13 + Y) / 5