Question

If 25 g of NH4Cl is dissolved at 80C, how many additional grams would be needed to make the solution saturated?

Answer 1

Here is a table showing the solubility of NH4Cl vs temperature. Solubility NH4Cl vs Temperature. That's about 65 g at 80 C. That should allow you to calculate how much must be added to 25 g to make it saturated.
https://en.wikipedia.org/wiki/Solubility_table