If velocity of a galaxy relative to earth is 1.2 × 106 ms^–2 then % increase in wavelength of light from galaxy as compared to the similar source on earth will be 

0.4 %

$ \frac{v}{c} = \frac{\Delta \lambda}{\lambda}$

$\frac{\Delta \lambda}{\lambda} = \frac{v}{c} \times 100\% = \frac{1.2\times 10^6}{3\times 10^8} \times 100\% = 0.4\%$