Teacher Li saw an English dictionary in Xinhua Bookstore, and it was 81 yuan on sale with a 10% discount. After bargaining, the salesperson agreed to sell it to Teacher Li at a 20% discount. How much did Mr. Li pay for this English dictionary?
李老师在新华书店看到一本英语字典，打九折出售是81元．经过还价，营业员同意打八折卖给了李老师．李老师买这本英语字典花了多少元？
<gadget id="calculator">90 / 100</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">81 / (9/10)</gadget>
<output>90</output>

<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">90 * (4/5)</gadget>
<output>72</output>

<result>72</result>