Question

To get 150g of a 12% solution, do you need more salt than to get 120g of a 15% solution?

Answer 1

we know that
Percent by mass (m/m) is the mass of solute divided by the total mass of the solution, multiplied by 100 %

so
mass of solute=Percent by mass*total mass of the solution/100%

case a) 150 g of a 12% solution
mass a solute=12%*150 g/100%------> 18 g

case b) 120 g of a 15% solution
mass a solute=15%*120 g/100%------> 18 g

the mass of solute (salt) is the same both cases