Someone, please help!! cant understand

Answer:
4400 N
Explanation: (c)
P= [tex]\frac{F}{A}[/tex]
F= PA
P= pressure
A= area
P=800x[tex]10^{3\\[/tex] and A= 5.5 x [tex]10^{-3}[/tex][tex]m^{2}[/tex]
Force F= 800x[tex]10^{3}[/tex]x0.0055= 4400 N
force exerted by the gas on the piston is 4400 N