What is the average of the three numbers? After adding 100, the average of the four numbers is 115.
三个数的平均数是多少，加上100后，四个数的平均数是115．
<gadget id="calculator">115 * 4</gadget>
<output>460</output>

<gadget id="calculator">460 - 100</gadget>
<output>360</output>

<gadget id="calculator">360 / 3</gadget>
<output>120</output>

<result>120</result>