(3 5/21 - 2 9/14 ) * 1 13/15 : ( 1 1/6 + 1 1/3)​

(3 5/21 - 2 9/14 ) * 1 13/15 : ( 1 1/6 + 1 1/3)=

=-6 2/3

3 5/21 - 2 9/14=68/21-37/14=(68*2-37*3)/42=25/42

1 1/6 + 1 1/3=7/6-4/3=(7-4*2)/6=-1/6

25/42*1 13/15=25/42*28/15=(5*4)/3*6=20/18=10/9

10/9:(-1/6)=-(10*6)/9*1=-20/3=-6 2/3