The wavelength of light recieved from a galaxy is 10% greater than that recieved from identical source on the earth .The velocity of the galaxy relative to the earth is

Dear student, 
Given,
(ΔΛ/Λ ) =10%=0.1
where Λ is wavelength.
percentage increases of wavelength related to velocity by
(ΔΛ/Λ) = (v/c)        (c= 3×10⁸ m/a = speed of light)
》0.1 = v/c
》v= (0.1×c)
》 v= 0.1×3×10⁸ =3×10⁷ m/a
therefore  velocity of galaxy  with  respect  to the  earth  is
3×10⁷ m/s.

Regards.