Выполнить действие 5/9+7/8
9/20-5/12
9/10-(3/5+1/6)+2/3

5/9 + 7/8 = 40/72 + 63/72 = 103/72 = 1 31/729/20 - 5/12 = 27/60 -25/60 = 2/60 = 1/309/10 - (3/5 + 1/6) + 2/3 = 9/10 - (18/30 + 5/30) + 2/3 = 9/10 - 23/30 +2/3 = 27/30 - 23/30 + 20/30 = 24/30 = 4/5