The roster form of "the set of the months in a year that ends with the letter 'y'" is
{January, February, May, July}
The months of the year are January, February, March, April, May, June, July, August, September, October, November, December.
Months of the year that ends with the letter 'y' are: January, February, May and July
There the roster form of "the set of the months in a year that ends with the letter 'y'" is {January, February, May, July}