A 2.00 mL sample is analyzed for phosphate by diluting the sample to 100.0 mL and measuring the absorbance at 700 nm. This solution's absorbance is 0.375. A 5.00 mL standard phosphate solution containing 45.0 mg of phosphate per liter is added to a second 2.00 mL sample and diluted to 100.0 mL. The absorbance of this solution is 0.506 at 700 nm. Calculate the concentration of phosphate in the original sample in mg/L.