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

### Instruction:
 Tony exercises every morning by walking 3 miles carrying a 25-pound backpack, then he runs another 10 miles without the backpack.  If he walks at a speed of 3 miles per hour and runs at a speed of 5 miles per hour, how many hours each week does he spend exercising?


### Response:
 Tony marche 3 miles à 3 miles par heure pendant 3/3=1 heure.
Tony court aussi 10 miles à 5 miles par heure pendant 10/5=2 heures.
Ainsi, chaque jour, il fait de l'exercice pendant 1+2=3 heures.
Au cours d'une semaine, il fait de l'exercice pendant 3*7=21 heures.