The average of 5 numbers is 18, and the average of the first 3 numbers is known to be 16, what is the average of the last two numbers?
5个数的平均数是18，已知前3个数的平均数是16，那么后两个数的平均数是多少．
<gadget id="calculator">18 * 5</gadget>
<output>90</output>

<gadget id="calculator">16 * 3</gadget>
<output>48</output>

<gadget id="calculator">90 - 48</gadget>
<output>42</output>

<gadget id="calculator">42 / 2</gadget>
<output>21</output>

<result>21</result>