For a kind of magazine, the wholesaler discounts 30% off the fixed price and wholesales it to the book stall owner. After the original price is reduced by 10%, the stall owner sells it to readers at 7.2 yuan per copy. Find out how much profit the stall owner makes from each copy sold.
一种杂志，批发商按定价打七折批发给书摊主，摊主将原定价格降价10%后以每本7.2元卖给读者，求每卖出一本摊主从中盈利多少元．
<gadget id="calculator">10 / 100</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 - (1/10)</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">7.2 / (9/10)</gadget>
<output>8</output>

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

<gadget id="calculator">8 * (7/10)</gadget>
<output>28/5 = around 5.6</output>

<gadget id="calculator">7.2 - (28/5)</gadget>
<output>1.6</output>

<result>1.6</result>