Below is an instruction that describes a task. Write a response that appropriately completes the request in French. Please answer in French.

### Instruction:
 James is building a hall of mirrors. Three of the walls will be completed covered with glass. If two of those walls are 30 feet by 12 feet and the third is 20 feet by 12 feet, how many square feet of glass does he need?


### Response:
 Tout d'abord, calculez combien de pieds carrés l'un des murs longs nécessite : 30 pieds * 12 pieds = <<30*12=360>>360 pieds carrés
Ensuite, doublez cette quantité car il y a deux murs : 360 pieds carrés * 2 = <<360*2=720>>720 pieds carrés
Ensuite, calculez combien le mur court nécessite : 20 pieds * 12 pieds = <<20*12=240>>240 pieds carrés
Ensuite, ajoutez cette quantité à la quantité des deux murs longs pour trouver la quantité totale de verre nécessaire : 720 pieds carrés + 240 pieds carrés = <<720+240=960>>960 pieds carrés