Ответ:
Пошаговое объяснение:
2/9+9/11=22/99+81/99=103/99=1 4/99
5/18+2/3=5/18+12/18=17/18
17/21+9/14=34/42+27/42=61/42=1 19/42
23/27+11/15=115/135+99/135=214/135=1 79/135
2/3-2/5=10/15-6/15=4/15
2/9-1/18=4/18-1/18=3/18=1/6
21/34-8/17=21/34-16/34=5/34
12/25-12/35=84/175-60/175=14/175