I've edited the original question because there was a mistake in it.

can x and y be determined if it is given that there are 65 values which the sum a multiple of x and a multiple of y cannot give

I.e. Nx + My has 65 unattainable values, where N and M are variables. Also x and y both do not equal 2.

I saw it on: Hard math questions, again? - Yahoo! Answers

Its the last part to the last question.