Question 589057
I think that you are misunderstood the problem because you can not cancel 6x from the numerator and denominator
(6x -42)/6x = 

First factor out the numerator 6x -42 = 6(x - 7)

Then you simplify by cancelling 6

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

Hope it helps:)
John10