Is 2 x+6-x=1/3(3x+18) a one solution ,no solution ,or an infinite numbers of solutions

To determine this, the first thing we should do is simplify the expression. As usual, bring like terms to either side of the "=" and then simplify.
2x + 6 - x = 1/3 (3x + 18)
x + 6 = 1/3 (3x + 18)
x + 6 = 1/3 (3x) + 1/3(18)
x + 6 = x + 6

We can already see that both sides have the same expression "x+6". Now, if you try to simplify any further, you will get 0=0. That means that for any value of x, the expression will simplify to 0=0. Because 0=0 is a true statement, for every value of x, the expression will be true. Therefore, there are an infinite number of solutions.

Hope this helped!! :D
Note: If you are still confused, let me know. I realize that I might have been a bit confusing in my explanation