The number of watermelons shipped by the fruit shop is twice the number of cantaloupe. If 30 watermelons and 20 cantaloupe are sold every day, there will be 60 watermelons left after the cantaloupe is sold out. How many watermelons did the fruit shop ship?
水果店运来的西瓜个数是哈密瓜个数的2倍，如果每天卖30个西瓜和20个哈密瓜，则哈密瓜卖完后还剩下60个西瓜．问水果店运来西瓜多少个？
<gadget id="calculator">2 * 20</gadget>
<output>40</output>

<gadget id="calculator">40 - 30</gadget>
<output>10</output>

<gadget id="calculator">60 / 10</gadget>
<output>6</output>

<gadget id="calculator">30 * 6</gadget>
<output>180</output>

<gadget id="calculator">180 + 60</gadget>
<output>240</output>

<result>240</result>