7/9x+4=2/3x+8 решение: 1/2x+1/6x=x-3 решение:

7/9х - 2/3х = 8 - 4                     1/2х + 1/6х - х = -3          

7/9х - 6/9х = 4                          3/6х + 1/6х - х = - 3

1/9х = 4                                    4/6х - х = - 3 

х = 4 : 1/9 = 4 * 9/1                  -2/6х = - 3

х = 36                                       х = - 3 : (- 2/6) = -3 * (-6/2)

х = 36                                       х = 18/2 = 9