Add 6 to 3 times a number, then subtract 9, and finally multiply by 2, the result is 60, what is this number?
一个数的3倍加上6，再减去9，最后乘上2，结果是60，这个数是多少．
<gadget id="calculator">60 / 2</gadget>
<output>30</output>

<gadget id="calculator">9 - 6</gadget>
<output>3</output>

<gadget id="calculator">30 + 3</gadget>
<output>33</output>

<gadget id="calculator">33 / 3</gadget>
<output>11</output>

<result>11</result>