A road is 810 meters long, and the repaired ones are 3 meters shorter than the unrepaired ones. How many meters are the unrepaired ones?
一条路长810米，已经修好的比未修好的2倍少3米，未修好的有多少米？
<gadget id="calculator">810 + 3</gadget>
<output>813</output>

<gadget id="calculator">2 + 1</gadget>
<output>3</output>

<gadget id="calculator">813 / 3</gadget>
<output>271</output>

<result>271</result>