The price of schoolbags in the shop has been reduced (1/4), and then increased (1/5). Finally, the price of schoolbags is 18 yuan, what is the original price?
商店书包降价了(1/4)，又提价了(1/5)，最后书包的标价是18元一个，原价是多少元一个．
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 + (1/5)</gadget>
<output>6/5 = around 1.2</output>

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

<gadget id="calculator">1 - (1/4)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">18 / (6/5) / (3/4)</gadget>
<output>20</output>

<result>20</result>