Calculating Molality: Solution Density and Molarity Relationship

[santoki]

Question
A 1.392 M sodium carbonate solution has a density of 1.1353 g/mL. Calculate the molality of the solution.

Attempt
1.392 M Na₂CO₃ = 1.392 mol Na₂CO₃ per 1 L solution

I can't really make sense out of this. What would be the next step?

 

[Borek]

What is the definition of molality?

Assume you have 1L of the solution. What is its mass? What is the mass of dissolved sodium carbonate? What is the mass of the solvent?