(1 2/5)2:1 2/5 - 5/6=17/30
28-27 6/7=1 6/7
17/30×4 2/7=17/7=2 3/7
1 6/7×53=98 3/7
98 3/7+2 3/7 = 100 6/7
(1 2/5)2:1 2/5 - 5/6=17/30
28-27 6/7=1 6/7
17/30×4 2/7=17/7=2 3/7
1 6/7×53=98 3/7
98 3/7+2 3/7 = 100 6/7