$d=1 \cdot 25\, g / mL$, conc, of solution $=3\, M$
$=3$ moles in one litre of the solution.
Molar mass of $NaCl =23+35 \cdot 5=58 \cdot 5\, g\, mol ^{-1}$
Volume of solution $=1 \, L =1000\, mL$
Mass of solution $=d \times V$
$=1 \cdot 25 \, g\, mL ^{-1} \times 1000 \, mL$
$=1250\, g$
Mass of solute $( NaCl )= n \times$ molar mass
$=3 \times 58 \cdot 5: 175 \cdot 5\, g$
Mass of solvent
= Mass of solution $-$ mass of solute
$=1250-175.5=1074.5\, g$