Answer: 87atm
Step-by-step explanation:
Ideal gas equation is given by the formular: PV = nRT
P = ? V = 2L , n = 6moles 
R = 0.082057 L.atm/mol/K
T = 80° C + 273.15 = 353.15K
Let's make 'P', the subject of formula, 
P = nRT/ V
 = 6mol x 0.082057 L.atm/mol/K. 
 x 353.15K / 2L
 = 86.9 approximately 
 = 87atm