61. Solving a chemistry problem

At λ=620 nm, the optical density of a solution containing 8.55*10-5 mol/l of component Q was 0.326, and the optical density of a solution R of a concentration of 2.37*10-4 mol/l was 0.055 at the same wavelength. Calculate the optical density of the solution containing 1.61*10-4 mol/l Q and 7.35*10-4 R at λ=620 nm. In all cases, the measurement was carried out at l=1 cm.