The naughty house is 300 meters east of the school, recorded as +300 meters. Now he walks westward from his home, and walks 150 meters per minute. How much can he record his position after 5 minutes?
淘气家在学校东面300米处，记作+300米．现在他从家向西走，每分钟走150米，5分钟后他所在的位置可以记作多少．
<gadget id="calculator">150 * 5</gadget>
<output>750</output>

<gadget id="calculator">750 - 300</gadget>
<output>450</output>

<result>450</result>