Well we compared two decimal numbers and found that 0.2 is greater than 0.15. Some students would argue that 0.15 is a longer decimal with more digits, and is therefore greater than 0.2. But they are wrong.
0.2 can be put as: 1/5( as a fraction) 20% (as a percent)
0.15 can be put as: 3/20 (asa fraction) 15% ( as a percent)