The average of two numbers is 150, one of which is 130, what is the other number.
两个数的平均数是150，其中一个数是130，另一个数是多少．
<gadget id="calculator">150 * 2</gadget>
<output>300</output>

<gadget id="calculator">300 - 130</gadget>
<output>170</output>

<result>170</result>