The freezing point of a 4% aqueous solution of X is equal to the...

Freezing point depression refers to the lowering of the freezing point of solvent upon the addition of solute.

${\left({\Delta T}_{f}\right)}_{X} = {\left({\Delta T}_{f}\right)}_{Y}$

${k}_{f}{m}_{x} = {k}_{f}{m}_{y}$

$\dfrac{4 \times 1000}{A \times 96} = \dfrac{12 \times 1000}{M \times 88}$

$M = 3 .27 A$

$≃ 3A$