With the information you have gained from the three known standards you can now determine the concentration of EDMAB in the final "unknown" cuvette. Since the molar absorptivity is an intensive property, it will be the same for EDMAB in all these solutions. Use the molar absorptivity just calculated, the pathlength, and the absorbance measured for the "unknown" cuvette to solve for the concentration (c) of EDMAB using the Beer-Lambert law. The idea is that the absorbance, A, is the y-value and the product e * b is the slope while c, the concentration, is the x-value of the plot.