Liquid Solution

When $9.2 \times 10^{-3} \mathrm{~kg}$ of formic acid is added to 600 ml of water the freezing point of water is depressed. If $30 \%$ of Formic acid undergoes dissociation what would be the freezing point of the solution? ( $\mathrm{K}_{\mathrm{f}}$ of $\mathrm{H}_2 \mathrm{O}$ is 1.86 K kg mol ; MM of formic acid: 46 amu )