Given :
An aqueous solution of 30g of salt in 80g of water.
To Find :
The % mass of the salt.
Solution :
Mass percentage of the salt is given by :
[tex]Mass \ \% = \dfrac{Mass \ of \ salt}{Mass \ of \ salt + Mass \ of \ water}\\\\Mass \ \% = \dfrac{30}{30 + 80 }\times 100 \%\\\\Mass \ \% = 27.27\ \%[/tex]
Hence, this is the required solution.