How would one be able to identify the lambda max of Cr(III) at a concentration less than 70ppm from a graph? I couldn't post the graph, but I don't understand how one would be able to do this? Can you please justify the answer with an explanation? I would want to know how and why...

The graph had the Chromium Absorbance Spectra of 70ppm for Cr(VI) and Cr(III). Cr(VI) intersects the curve for Cr(III) at one point.
It is possible to detect Cr(III) in the presence of Cr(VI) using a lambda max of 560-580nm.
Cr(VI) exhibits 2 absorption bands, one with lambda max of 348nm and a 2nd broader band with lambda max of 435nm.
Cr(III) has 2 absorption bands one with lambda max of 405nm and one with lambda max of 576nm.