Answer: The new pressure is 0.39 bar
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 = 1.2 bar
= final pressure of gas = ?
= initial volume of gas = 20.0 ml
= final volume of gas = 80.0 ml
= initial temperature of gas = 
= final temperature of gas = 
Now put all the given values in the above equation, we get:


The new pressure is 0.39 bar