[ \textAbsorbance = m \times \textConc + c ]
For unknown absorbance = 0.415:
If the unknown was diluted (e.g., 10×), multiply by the dilution factor:
[ 0.415 = 0.831 \times \textConc + 0.001 ] [ \textConc = \frac0.415 - 0.0010.831 = 0.498 \text mg/mL ]