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

### Instruction:
Phil likes to collect baseball cards.  He buys a pack of twenty each week for a year, but then loses half of them one day in a fire.  How many baseball cards does Phil have left?

### Response:
A year of collecting twenty cards each week means 52*20= <<1040=1040>>1040 baseball cards.
But half of them are destroyed in the fire, leaving 1040/2=<<1040/2=520>>520 baseball cards that Phil has left.
#### 520