bhaskar438
I agree that the new constraint, X+Y<79, makes the problem better. I think before the new constraint, the problem was out of GMAT scope because it would be too time consuming to figure out whether there exists two numbers that add up to 97 whose product is a number that is 77 more than a multiple of 79. I had to write my own simple program to find out that there is no such numbers.
Yes, this was not GMAT like task. Now it is better )
Thanks for your efforts in checking right answer.
No problem. This was an excellent question!