Lithium is often used as an internal standard for the measurement of sodium. A 6.0 ppm solution of Lit gives an emission signal of 62.9 units when measured at 671 nm, and a 6.0 ppm solution of Nat gives an emission signal of 48.2 units at 589 nm. A 50.0 mL aliquot of unknown solution containing Nat is mixed with at 10.0 mL solution containing 50.0 ppm Lit and is found to give an emission signal of 51.8 units at 589 nm and 79.5 units at 671 nm. What was the concentration of Nat in the original sample? (8 pts)