The average of 5 numbers is 38, the average of the last four numbers is 35, what is the first number.
5个数的平均数是38，后四个数的平均数是35，第一个数是多少．
<gadget id="calculator">38 * 5</gadget>
<output>190</output>

<gadget id="calculator">35 * 4</gadget>
<output>140</output>

<gadget id="calculator">190 - 140</gadget>
<output>50</output>

<result>50</result>