There are 3 ropes with a total length of 240 meters. The first rope is 20 meters shorter than the second rope, and the third rope is twice as long as the first rope. What is the length of the third rope?
有3条绳子共长240米，第一条比第二条短20米，第三条是第一条的2倍，第3条绳子长多少米．
<gadget id="calculator">240 - 20</gadget>
<output>220</output>

<gadget id="calculator">1 + 2 + 1</gadget>
<output>4</output>

<gadget id="calculator">220 / 4</gadget>
<output>55</output>

<gadget id="calculator">2 * 55</gadget>
<output>110</output>

<result>110</result>