A jar full of whisky contains $40\%$ of alcohol. A part of this whisky is replaced by another containing $19\%$ alcohol and now the percentage of alcohol was found to be $26$. The quantity of whisky replaced is :

- $\frac{2}{5}$
- $\frac{1}{3}$
- $\frac{2}{3}$
- $\frac{3}{5}$