The value of y if $\frac{2}{x}+\frac{1}{y}=3 and \frac{-2}{x}+\frac{1}{y}=4$ is______ .

Let $\frac{1}{x}=p$ and $\frac{1}{y}=q$ 

Then, we get, 

2p + q = 3     ...(i)

-2p + q = 4    ...(ii)

Adding we (i) and (ii) get, 2q=7 

Or, $q=\frac{7}{2}$ 

Then, $\frac{1}{y}=\frac{7}{2} or, y=\frac{2}{7}$