Data Sufficiency

if xn is different from cero, what is the value of S?

S= (2/n) / 1/x + 2/3x

1) x=2n
2) n=1/2

As we don't have the value of S, this is an equation with 3 unknowns: S, x and n.

1) Given the ratio between n and x the equation can be solved without solving the exercise, as it implies one equation with only one unknown (S).

2) It is obvious that the second option is imposible to be solved as we will still have 2 unknows (S and X) in only one equation.

Solved in 20 seconds... Is my reasoning right?

yes, full marks to you