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

### Instruction:
 Mark spent 220 dollars to fix his car. It needed two parts that cost 20 dollars each, and labor cost .5 dollars a minute. How many hours did the mechanic work?


### Response:
 Le coût de la main-d'œuvre est de 0,5*60=<<.5*60=30>>30 dollars par heure.
20+20=<<20+20=40>>40 dollars pour les pièces.
220-40=<<220-40=180>>180 dollars pour la main-d'œuvre.
180/30=<<180/30=6>>6 heures.