The pressure : 800 kPa
Boyle's law and Gay Lussac's law
[tex]\tt \dfrac{P_1.V_1}{T_1}=\dfrac{P_2.V_2}{T_2}[/tex]
P1 = initial gas pressure (N/m² or Pa)
V1 = initial gas volume (m³)
P2 = gas end pressure
V2 = the final volume of gas
T1 = initial gas temperature (K)
T2 = gas end temperature
The pressure after the gas is compressed :
[tex]\tt \dfrac{100\times 6.4}{300}=\dfrac{P_2\times 2.4}{900}\\\\P_2=800~KPa[/tex]