Answer:
[tex]\%m/m = 10\,\%[/tex]
Explanation:
El porcentaje masa a masa de la solución se obtiene al dividir la masa del cloruro de sodio por la masa del agua (The mass-mass percentage of solution is obtained by dividing the mass of sodium chloride by the mass of water):
[tex]\%m/m = \frac{20\,g}{200\,g}\times 100\,\%[/tex]
[tex]\%m/m = 10\,\%[/tex]