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

### Instruction:
 Mark constructed a deck that was 30 feet by 40 feet. It cost $3 per square foot. He then paid an extra $1 per square foot for sealant. How much did he pay?


### Response:
 Le deck mesure 30 pieds sur 40 pieds, soit une superficie de 1200 pieds carrés.
Le deck coûte 1200 * 3 = 3600 $.
Il a payé un supplément de 1200 * 1 = 1200 $ pour le scellant.
Donc, le coût total est de 3600 + 1200 = 4800 $.