pls help

You wish to design an assay to measure glucose concentration in the range of 01.0 mg/ml. You plan to make 6 test tubes with 6 different glucose concentrations. The total volume in each test tube should be 1200L. In addition to glucose, you also want the test tube buffered at a concentration of 50mM sodium phosphate. Available to you are: 1) A6.00mg/mL stock glucose solution 2) A 150. mM stock sodium phosphate buffer solution. 3) Water To prepare your test tube to assay 0.2mg/mL glucose, how many mL of water should you add