According to the Gay-Lussac's Law, if an ideal gas is at constant volume, then the quotient of its pressure and its temperature is also constant:
![(P_1)/(T_1)=(P_2)/(T_2)](https://img.qammunity.org/2023/formulas/chemistry/college/bl01ihqrk2iafik946ln2z6l66er35i8vj.png)
If the final temperature is 1.2 times the initial temperature, then, substitute T_2=1.2*T_1 and solve for P_2:
![\begin{gathered} T_2=1.2T_1 \\ \Rightarrow(P_1)/(T_1)=(P_2)/(1.2T_1) \\ \Rightarrow P_2=(P_1)/(T_1)*1.2T_1 \\ \Rightarrow P_2=1.2P_1 \end{gathered}](https://img.qammunity.org/2023/formulas/physics/college/tp1tguyvn6jms0x6aawdebzk2pk99mezup.png)
Therefore, the final pressure of the gas is 1.2 times the initial pressure.