It would be sometimes because it can be 82.2% but if you round it the closest one would be 80% if it was 84.7% its closer to 85 so it would be 85% I hope I helped you out rate the answer if I got it right thanks!
You should be able to set up a proportion between the sides something like (18+x)/x=(56+21)/56
Answer:
dont lie, thats only 5 points
3.1 as a decimal. And it as a mixed number wait a sec.......3 1/10
Hope I could help! :)