The BSA standard solution with the concentration of 0.5 mg/mL was used to produce standard curve for protein assay based on Bradford method The test tubes contains BSA solutions was prepared: 0, 20, 40, 60, 80, 100 ul. The reading of the absorbance for each test tube after adding the Bradford reagent was 0, 0.05, 0.09. 0.14, 0.19 and 0.22. If 20 ul of protein solution with unknown concentration were taken and mixed with 80 ul. water. Then, 10 L of this mixture was reacted with Bradford reagent and the absorbance reading was 0.08. What is unknown protein solution concentration before dilution?