1. an ipod that costs $110 was marked up by 50%.
markup:
selling price:
2. a television that costs $360 was marked up by 25%.
markup:
selling price:
3. a shirt that costs $12.50 was marked up by 30%
markup:
selling price:

1.Markup: $55 
   110+55=165
2. Markup: $90
   360+90=450
3. Markup: $3.75
   12.50+3.75=16.25

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.