Répondre :
volume de la pièce = 3*3.5*3.1= 32.55 m3
volume des meubles = 10% du volume total = 32.55*0.1=3.255 m3
volume restant = 32.55-3.255 = 29.295 m3
volumes dioxygène = 20% du volume => 29.295 * 0.2 = 5.859 m3
volume diazote = 80% du volume => 29.295*0.8 = 23.436 m3