The optical rotation of a sucrose solution was measured, in order to determine its concentration, and it was found +19.95° using a 15 cm cuvette. A sucrose solution at 100 g.L-1, in a 10 cm tank, shows an optical rotation of +6.65°. What is the concentration of the first solution? What is the value of the specific optical rotation of sucrose (at the temperature where the measurement was made, and for the wavelength of the light used?