A section of road is 800 meters long and has been repaired for 5 days, 90 meters per day. How many meters are left unrepaired?
一段公路长800米，已经修了5天，每天修90米．还剩多少米没有修？
<gadget id="calculator">90 * 5</gadget>
<output>450</output>

<gadget id="calculator">800 - 450</gadget>
<output>350</output>

<result>350</result>