Answer:
Option D
Explanation:
Water content in the original mixture $= 56\times \left(\frac{2}{7}\right)$ $=16$ litres
Let $x$ litre of water be added to get the required ratio
$\frac{16+x}{56+x}=\frac{5}{4+5}$
$144+9x$ $= 280 + 5x$
$4x = 136$
$x = 34$ litres