@dev30 There is only one method, as we come to know that xy=12, initially I felt that we can
(x,y) pairs can be (3,4) and (2,6) that indirectly means (39,52) and (26,78), i ignored the pair (1,12). Later I feel that (26,78) in not correct because the HCF of 26 and 78 is 26 only but we need the HCF should be 13 right?? and so only I took 13X156 will be second pair.
Finally, the 39X52 and 13X156 are the pairs..
Please let me know if am not clear..
d pair should be like this that they should be prime no. to each other..otherwise wont come hcf would be 13...:)