what is 1/7x+2/3-1/6x-2/9

Find common denominators:

(1/7)x - (1/6)x  = (6/42)x - (7/42)x  =  (-1/42)x

(2/3) - (2/9)  =  (6/9) - (2/9)  =  4/9

Answer:  (-1/42)x + (4/9)

If you're having trouble finding common denominators, ask about them.