5/6 - 2/3 = 5/6 - 4/6 = 1/6
1/6+2/3=1/6+4/6=5/6 верно
17/18 - 5/6 = 17/18 - 15/18 = 2/18 =1/9
1/9+5/6=2/18+15/18=17/18 верно
5/8 - 5/24 = 15/24 - 5/24 = 10/24 = 5/12
5/12+5/24=10/24+5/24=15/24=5/8 верно
1/2 - 3/10 = 5/10 - 3/10 = 2/10 = 1/5
1/5+3/10=2/10+3/10=5/10=1/2 верно