A Distant Galaxy Is Emitting Light from the Helium Spectrum

Short Answer

A distant galaxy is emitting light from the helium spectrum at 388.9 nm.On Earth the wavelength of the light from this galaxy is measured to be 540.6 nm.Estimate how far from Earth (in light-years)this galaxy is if the Hubble constant has the value 22 km/s per million light-years. (c = 3.00 × 10⁸ m/s,1 ly = 9.461 × 10¹⁵ m,1 y = 3.156 × 10⁷ s)