80 over 84 simplified = 20/21
62/80 = 77.5%
80/231 cannot be simplified.
35/80 simplified is 7/16.
31 over 62 can be simplified to one half
80 over 36 simplified: 20 over 9 and as a mixed number it's 2 2/9
23/80 cannot be simplified further.
62/125
31/50
1/2
8/31
31/66