3(целых) 9/14: (1(целая)3/7-5/21*0.9)-0.76

1) 3целых 9/14 : 1цеелую 3/7 = 51/14: 10/7= 51/14* 7/10 = 51/10.
2) 5/21 * 9/10 = 9/42.
3) 51/10 - 9/42 = (1071 - 90)/420 = 981/420 = 2целых 141/420.
4) 2 целых 141/420 - 76/100 = 2 целых 141/420 - 19/25 = 2 целых(705 - 15960/2100=
= 1 ЦЕЛАЯ (2805 -1596)/2100 = 1 ЦЕЛАЯ 1209/2100= 1 ЦЕЛАЯ403/700