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?
The difference between the initial cost and the amount she sold the phone for is $300-$255 = $
<gadget id="calculator">300-255</gadget>
<output>45</output>
45
$45 is (($45/$300)*100)% = 15% of $300.

<result>15</result>