Steam at $100^\circ\text{C}$ is passed into $20\,\text{g}$ of water at $10^\circ\text{C}$. When water acquires a temperature of $80^\circ\text{C}$, the mass of water present will be: [Take specific heat of water $= 1\,\text{cal g}^{-1}\;^\circ\text{C}^{-1}$ and latent heat of steam $= 540\,\text{cal g}^{-1}$]