When the numerator of a fraction is increased by $4$, the fraction increases by $2/3$... When the numerator of a fraction is increased by $4$, the fraction increases by $2/3$. What is the denominator of the fraction?
I tried,
Let the numerator of the fraction be $x$ and the denominator be $y$.
Accordingly, $$\frac{x+4}y=\frac xy+\frac 23$$
I am not able to find the second equation. 

Given,
$$\frac{n+4}{d}=\frac{n}{d}+\frac{2}{3}$$
So,
$$\frac{n}{d}+\frac{4}{d}=\frac{n}{d}+\frac{2}{3}$$
Or,
$$\frac{4}{d}=\frac{2}{3}$$
That, gives us $d=6$ 
