1) 2 -3 1/7×(2 -1 9/11)÷8/21 2) 1 3/8 × 3/5-3/5×1/8 3) 2 - 3 1/7×(2-1 9/11): 8/21 4) 4 5/12-1 1/2: (2 1/6+8/15)×1 4/5

1) 11 ( 5/11 ) - 8 ( 21/22 ) = 11 ( 10/22 ) - 8 ( 21/22 ) = 10 ( 32/22 ) - 8 ( 21/22 ) =
= 2 ( 11/22 ) = 2 ( 1/2 ) 
2) 2 ( 1/2 ) : 1 ( 2/3 ) = 5/2 : 5/3 = 3/2 = 1,5
ОТВЕТ 1,5