Answer : The pressure (in atm) of the piston under these final conditions is, 0.857 atm
Explanation :
Combined gas law is the combination of Boyle's law, Charles's law and Gay-Lussac's law.
The combined gas equation is,

where,
= initial pressure of gas = 305.7 mmHg
= final pressure of gas = ?
= initial volume of gas = 847.1 mL
= final volume of gas = 228.1 mL
= initial temperature of gas = 357.8 K
= final temperature of gas = 205.2 K
Now put all the given values in the above equation, we get:


conversion used : (1 atm = 760 mmHg)
Thus, the pressure (in atm) of the piston under these final conditions is, 0.857 atm