A chemist has a hot solution, saturated at $80\ ^\circ\text{C}$, made with $150\ \text{g}$ of water. The salt in it dissolves $71\ \text{g}$ in each $100\ \text{g}$ of water at $80\ ^\circ\text{C}$, but only $12\ \text{g}$ at $20\ ^\circ\text{C}$. She lets it cool to $20\ ^\circ\text{C}$. How many grams of crystals can she filter off?