A book, each priced at 18.9 yuan. Wholesalers wholesale to bookstalls at "30% off" the price, and book stall owners sell to readers at "10% off" the price. How much money can a book stall owner earn by selling 100 such books?
一种书，每本定价18.9元．批发商按定价的"七折"批发给书摊，书摊摊主按定价的"九折"卖给读者．卖100本这样的书，书摊摊主能赚多少钱？
<gadget id="calculator">90 / 100</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">18.9 * (9/10)</gadget>
<output>17.01</output>

<gadget id="calculator">70 / 100</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">18.9 * (7/10)</gadget>
<output>13.23</output>

<gadget id="calculator">17.01 - 13.23</gadget>
<output>3.78</output>

<gadget id="calculator">3.78 * 100</gadget>
<output>378</output>

<result>378</result>