Question 314697
This isn't really an algebra problem.
Find the number of moles of NaCl.
Molecular weight of NaCl=58.44 g/mole
15g of NaCl=(15/58.44)=0.257 moles NaCl
Molarity is moles per unit volume.
M=0.257 moles/3 L=0.0857 m/L