the ink in a pen will last for 12 pages where each pages 32 lines how many pages will half the ink last if there are 48 lines per page and there are now 20% fever letters per line then in earlier case​

The first one, i believe, would be correct. all the others have one thing in common, and that's that they have repeating numbers. in the second one, x and y have repeating 6's and 3's, and in the third, x and y have repeating 6's as well. in the last one, there are repeating 3's. the first one has no repeating numbers.