Find mass % given Molarity and Density of solution

The question is:

Determine the mass % of sodium chlorite in a 4.197 M aqueous solution of sodium chlorite. The density of the solution is 1.3 g mL-1.

I don't really know how to differentiate between the grams of sodium chlorite and the grams of the total solution. Can someone walk me through it?

A 4.197 M solution has 4.197 moles of solute in 1 L (1000 ml) of solution

mass of 4.197 moles NaClO2 = moles x molar mass
= 4.197 mol x 90.442 g/mol
= 379.585074 g

there are 379.585074 g of NaClO2 in 1 L of the solution

density = mass / volume
Therefore mass = density x volume

total mass of 1000 ml solution = 1.3 g/ml x 1000 ml = 1300 g

% mass NaClO2 = mass NaClO2 / total mass solution x 100/1

= 379.585074 g / 1300 g x 100/1
= 29 % (2 sig figs)