I assume you mean
(x+ 6)/3 = (x+ 6)/x
The technique is to multiply both sides by 3 and then multiply both sides by x. This will eliminate the fractions.
3 (x+ 6)/3 = 3 (x+ 6)/x
x + 6 = (3x + 18)/x
Now multiply both sides by x to get
x (x + 6) = x (3x + 18)/x
x2 + 6x = 3x + 18
Now solve this quadratic which will give two solutions.
Make sure to verify your answer.