A bookstore sells a wall calendar priced at 12.5 yuan at a 20% discount, and gains a 25% profit as a result. What is the cost price of these calendars?
某书店将定价为12.5元的挂历降价20%出售，结果还获得了25%的利润．这些挂历的成本价是多少元．
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 + (1/4)</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">(4/5) / (5/4)</gadget>
<output>16/25 = around 0.64</output>

<gadget id="calculator">12.5 * (16/25)</gadget>
<output>8</output>

<result>8</result>