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

### Instruction:
 Bernie has a collection of 18 unique postcards. He decided to sell half his collection for $15 per postcard. After he has successfully sold his postcards he decided to spend all the earned money to buy new postcards for $5 each. How many postcards does Bernie have after all his transactions?


### Response:
 La moitié de la collection de Bernie signifie 18 * 0,5 = <<18*0.5=9>>9 cartes postales.
Il a donc réussi à vendre 9 cartes postales pour 9 * 15 = 135 $.
Il a décidé de dépenser tout son argent pour acheter de nouvelles cartes postales à 5 $ chacune, il a donc pu acheter 135 / 5 = 27 nouvelles cartes postales.
En ajoutant les nouvelles cartes postales aux anciennes, Bernie a donc 27 + 9 = <<27+9=36>>36 cartes postales.