2-(1 11/30-1.7) 1 2/7 : 1 13/14

2 - (1 11/30 - 1,7) - 1 2/7 : 1 13/14 = 1 2/3 

1) 1 11/30 - 1,7 = 1 11/30 - 17/10 = 1 11/30 - 51/30 = 41/30 - 51/30 = - 10/30 = - 1/3
2) 1 2/7 : 1 13/14 = 9/7 : 27/14 = 9/7 * 14/27 = 2/3
3) 2 - (- 1/3) = 2 + 1/3 = 2 1/3
4) 2 1/3 - 2/3 = 1 4/3 - 2/3 = 1 2/3

спасибо большое