Understanding absorption coefficient, extinction coefficient, optical density, and oscillator strength. Using the Beer-Lambert law to calculate the intensity of light after passage through a sample.

Light of wavelength 256 nm passes through a 1 mm path length cell that contains a 0.05 M solution of benzene.  The light is reduced to 16 percent of its initial value.  Calculate the optical density and extinction coefficient of the sample.  What would be the transmittance through a cell of path length 2 mm?