Grandma Wang built a long rectangular chicken coop against the wall with a fence. The chicken pen is 15 meters long and 10 meters wide. What is the total length of the fence?
王奶奶靠墙用篱笆围起一个长的这边靠墙的长方形的养鸡圈．鸡圈的长15米，宽10米．围成的篱笆共长多少米？
<gadget id="calculator">10 * 2</gadget>
<output>20</output>

<gadget id="calculator">15 + 20</gadget>
<output>35</output>

<result>35</result>