<human>:  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?
<bot>: How much did Matilda lose? ** The difference between the initial cost and the amount she sold the phone for is $300-$255 = $<<300-255=45>>45
What percentage of the initial cost did Matilda lose? ** $45 is (($45/$300)*100)% = 15% of $300
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