The solubility of KNO3 is 155 g per 100 g of water at 75°C and 38.0 g at 25°C. What mass (in grams) of KNO3 will crystallize out of solution if exactly 100 g of its saturated solution at 75°C is cooled to 25°C?

The textbook answer key says the answer is 45.9 grams, butto know how to solve it.explain with steps how to solve this.