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

### Instruction:
Matilda bought a smartphone for $300. Then she decided she wouldn't use it anyway and sold it for $255. What percentage of the initial cost did she lose?

### Response:
 $300 - $255 = $<<300-255=45>>45 was lost
$45 is (($45/$300)*100)=15% of $300
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