Calculating Minimum Molality of Antifreeze for -20F

[ap101]

Homework Statement

Ethylene Glycol, C2H602, (d=1.12 g/mL)
Antifreeze solution will protect engine for temperatures as low as -20F

Homework Equations

What is the minimum molality of antifreeze solution required?

The Attempt at a Solution

Need help starting.

 

[cdotter]

I assume you're mixing it with water. Which is the solvent and which is the solute? What is the freezing point of the pure solvent? Once you have that, you can determine the freezing point depression.