There is a batch of biscuits on the shelf of the supermarket. After selling (2/5), the salesperson adds another 12 packs. At this time, the number of packs of biscuits on the shelf is exactly 80% higher than the original one. How many packages of biscuits are there on the shelf?
超市货架上有一批饼干，卖出(2/5)后，营业员又加进了12包，这时货架上饼干的包数恰好比原来的80%．货架上原有饼干多少包？
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">(4/5) - (3/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">12 / (1/5)</gadget>
<output>60</output>

<result>60</result>