Вычислить (1/2: 3/4-4/9): 3/5, 1/2: 3/8-4/9: 3/5, 3/5: (9/10-3/5*8/9) и 3/5: 9/10-3/5*8/9 с решением примеры

(1/2:3/4-4/9):3/5,= (1/2 * 4/3 - 4/9) : 3/5 = (2/3 - 4/9) : 3/5 = (6/9 - 4/9) : 3/5 = 2/9 : 3/5 = 2/9 * 5/3 = 10/27
 1/2:3/8-4/9:3/5, = 1/2 * 8/3 - 4/9 * 5/3 = 4/3 - 20/27 = 45/27 - 20/27 = 25/27
3/5:(9/10-3/5*8/9) = 3/5 : ( 9/10 - 8/15) = 3/5 : (18/30 - 16/30) = 3/5 : 2/30 = 3/5 * 15/1 = 3/1 * 3/1 = 9
 и
 3/5:9/10-3/5*8/9 = 3/5 * 10/9 - 1/5 * 8/3 = 1/1 * 2/3 - 8/15 = 2/3 - 8/15 = 10/15 - 8/15 = 2/15