The average of two numbers is 160, one of them is 120, what is the other number.
两个数的平均数是160，其中一个数是120，另一个数是多少．
<gadget id="calculator">160 * 2</gadget>
<output>320</output>

<gadget id="calculator">320 - 120</gadget>
<output>200</output>

<result>200</result>