We used a laser rangefinder, commonly used in construction works to measure distance, alongside theoretical derivation to devise our own experimental methods to accurately measure the refractive index of aqueous solutions at room temperature. By comparing our methods with the optical pin method, it is evident that our measurement error is one significant figure smaller. Using our method, we were also able to discover the distinct linear relations between refractive index and liquids of different concentrations. Additionally, we were able to find that all refractive indexes bore the property of linear combination in two-solute aqueous solutions and two immiscible solutions.