1 . Выполните действие :
8/9 - 5/2
7/5+7/12
5/20+5/28
11/42-5/28

8/9 - 5/2 = 16/18 - 45/18 = - 29/18 = - 1ц. 11/18,7/5 + 7/12 = 84/60 + 35/60 = 119/60 = 1ц. 59/60,5/20 + 5/28 = 35/140 + 25/140 = 60/140 = 3/7,11/42 - 5/28 = 22/84 - 15/84 = 7/84 = 1/12