7 : (1 1/5 - 2,2) + 1/10 : (2,8 - 3/8) = - 6 целых 93/97
1) 1 1/5 - 2,2 = 1,2 - 2,2 = - 1
2) 7 : (-1) = - 7
3) 2,8 - 3/8 = 2 4/5 - 3/8 = 2 32/40 - 15/40 = 2 17/40 = 97/40
4) 1/10 : 97/40 = 1/10 * 40/97 = (1*4)/(1*97) = 4/97
5) - 7 + 4/97 = - 6 93/97
Пояснения:
1 целая 1/5 = 1 целая 2/10 = 1,2
2,8 = 2 целых 8/10 = 2 целых 4/5
4/5 = 32/40 - доп.множ. 8
3/8 = 15/40 - доп.множ. 5
2 целых 17/40 = (2*40+17)/40 = 97/40