A rectangular chicken farm is 10 meters long. If the length is reduced by 3 meters, the area will be reduced by 12 square meters. Now it is necessary to build a fence around the original chicken farm. How many meters is the fence?
一个长方形养鸡场长10米，如果长减少3米，面积就比原来减少12平方米．现在要在原来养鸡场的四周围上围墙，围墙长多少米？
<gadget id="calculator">12 / 3</gadget>
<output>4</output>

<gadget id="calculator">10 + 4</gadget>
<output>14</output>

<gadget id="calculator">14 * 2</gadget>
<output>28</output>

<result>28</result>