The average of four numbers is 60. If one number is removed, the average of the remaining three numbers is 66. What is the number removed?
四个数的平均数是60，若去掉一个数，剩下的三个数的平均数是66，去掉的数是多少．
<gadget id="calculator">60 * 4</gadget>
<output>240</output>

<gadget id="calculator">66 * 3</gadget>
<output>198</output>

<gadget id="calculator">240 - 198</gadget>
<output>42</output>

<result>42</result>