The single-point standard addition method was used in the determination of phosphate by the molybdenum blue method. A 5.00-mL urine sample was treated with molybdenum blue reagents to produce a species absorbing at 820nm, after which the sample was diluted to 100mL. A 10.00mL aliquot of this solution gave an absorbance of 0.428 (solution 1). Addition of 1.00mL of a solution containing 0.0700mg of phosphate to a second 10.0-mL aliquot gave an absorbance of 0.724 (solution 2). Use these data to calculate the concentration of phosphate in milligrams per milliliter of the urine sample