2целых 1/7×(1 целая 2/3+2 целых 7/9×3,6) с

2 1/7 =15/7

1 2/3 =5/3

2 7/9 =25/9

3.6 =36/10 =18/5

15/7 *(5/3 +25/9 *18/5) =
=15/7 *(5/3 +25*18 /9*5) =15/7 *(5/3 + 5*2) =15/7 *(5/3 +10) =15/7 *(5 +10*3)/3 =(15*35) /(7*3) =5*5 =25

1) 2 7/9 • 3,6 = 25/9 • 18/5 = 5 • 2 = 10
2) 1 2/3 + 10 = 11 2/3
3) 2 1/7 • 11 2/3 = 15/7 • 35/3 = 5 • 5 = 25
ответ 25