Help with a chemistry problem

This one's about molality/colligative properties.

A solution that contains 13.2 g of solute in 250.0 g of carbon tetrachloride (CCl4) freezes at -33 C. What is the molecular weight of the solute?

I know to use the equation m = Delta Tf / Kf
But I'm just confused as to what those are. And then once I find the molality, will I use that number to find the number of moles?
Any help is appreciated!

use...
dTfp = Kf x m x i

where..
dTfp = freezing point of pure solvent - freezing point of solution = -22.92°C - -33 = 10.1°C
Kf = cryoscopic constant for the solvent = 29.8°C/m
m = molality = moles solute / kg solvent
i = van't hoff factor = # ions 1 molecule solute dissociates into in solution

and a couple examples of "i"
1 NaCl --> 1 Na+ + 1 Cl-.. 1 formula unit ---> 2 ions.. i=2
1 MgCl2 ---> 1 Mg+2 + 2 Cl-.. 3 ions.. i=3
1 sucrose ---> 1 sucrose... it doesn't dissociate.. i=1

note that last one? if the solute doesn't dissociate, i=1.. most things don't dissociate in non polar solutes like CCl4 fyi.. so.. i=1 for this problem

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next..
solve for "m".. then mw.. like this.

dTfp = Kf x m x i
m = dTfp / (Kf x i)
m = (10.1°C) / (29.8°C/m x 1) = 0.339m

and finally..
moles solute = 0.250kg CCl4 x (0.339 moles solute / 1kg CCl4) = 0.0848
molar mass solute = 13.2g / 0.0848 moles = 156 g/mole

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questions?