Which equation has x=2/3 as a solution and why?

There are an infinite number of different equations that have
x=2/3  as the solution, or as one of several solutions.

You didn't show us your list of choices, so we can't help you
pick the right one.

Just take each choice, one at a time.  Write ' 2/3 ' in place of 'x'
in each equation, and simplify everything.  You'll wind up with
one equation that's true, and the others will say something that's
nonsense. 

The one that's true is the one that has  x=2/3  as its solution.