If it was 100, and it was marked up 30%, it's being marked up 30% of 100, which is 30. So the new price is $130.
However, when it is marked down 30%, it's marked down 30% of 130 (rather than the original 100). This amount is $39, reducing the price to $91.
So no, Walmart didn't break even on this one, but rather, lost $9 from the original price.
Poor Walmart. : )
Hope this helps, Linda!