(23цел.1/21:1цел.3/7-5,5)3,19-1цел.17/18

(23 1/21 : 1 3/7 - 5,5) : 3,19 - 1 17/18 = 1 целая 7/18

1) 23 1/21 : 1 3/7 = 484/21 : 10/7 = 484/21 * 7/10 = (242*1)/(3*5) = 242/15 =
= 16 целых 2/15
2) 16 2/15 - 5,5 = 16 2/15 - 5 5/10 = 16 4/30 - 5 15/30 = 15 34/30 - 5 15/30 =
= 10 целых 19/30
3) 10 19/30 : 3,19 = 319/30 : 319/100 = 319/30 * 100/319 = 100/30 = 10/3 =
3 целых 1/3
4) 3 1/3 - 1 17/18 = 3 6/18 - 1 17/18 = 2 24/18 - 1 17/18 = 1 целая 7/18

Объясненья:
23 целых 1/21 = (23*21+1)/21 = 484/21
1 целая 3/7 = (1*7+3)/7 = 10/7
5,5 = 5 целых 5/10 = 5 целых 15/30
10 целых 19/30 = (10*30+19)/30 = 319/30
3,19 = 319/100