A rectangular swimming pool is 50 meters wide and twice as long as it is wide. What is the circumference of this swimming pool in meters?
一个长方形游泳池的宽是50米，长是宽的2倍．这个游泳池的周长是多少米？
<gadget id="calculator">50 * 2</gadget>
<output>100</output>

<gadget id="calculator">100 + 50</gadget>
<output>150</output>

<gadget id="calculator">150 * 2</gadget>
<output>300</output>

<result>300</result>