Colligative Properties Questions

A $5.25\%$ solution of a substance is isotonic with a $1.5\%$ solution of urea (molar mass $=60{\text{g mol}}^{-1}$) in the same solvent. If the densities of both the solutions are assumed to be equal to $1.0{\text{g cm}}^{-3}$, molar mass of the substance will be: