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

### Instruction:
 Brian likes to read books. He read one book that had 20 chapters, two books that had 15 chapters each, and one book that had half the chapters of the three previous books put together. How many chapters of books did Brian read?


### Response:
 Brian a lu deux livres avec 15 chapitres, donc il a lu 2*15=30 chapitres.
Il a également lu un livre avec 20 chapitres, ce qui porte le total des trois premiers à 30+20=50 chapitres.
La moitié de cela est 50/2=25 chapitres, le nombre de chapitres dans le quatrième livre que Brian a lu.
Ainsi, au total, Brian a lu 30+20+25=75 chapitres.