1/3(3-6)-2/7(7x-21)=9
1/3 ( 3 - 6 ) - 2/7 ( 7х - 21 ) = 9 1/3 • ( - 3 ) - 2х + 6 = 9 - 1 - 2х + 6 = 9 - 2х = 9 - 5 - 2х = 4 х = - 2