A rectangular field is 40 meters long and 30 meters wide. Xiaoqiang walks along the field twice. How many meters will he walk in total?
一个长方形的球场，长是40米，宽是30米，小强沿着球场走两圈，他一共要走多少米
<gadget id="calculator">40 + 30</gadget>
<output>70</output>

<gadget id="calculator">70 * 2 * 2</gadget>
<output>280</output>

<result>280</result>