An ornamental vegetable pocket pumpkin, 50 yuan per pot, buy 4 pots and get one free. Aunt Wang buys 4 pots at a time, how much is each pot cheaper?
一种观赏蔬菜袖珍南瓜，每盆50元，买4盆送一盆．王阿姨一次买4盆，每盆便宜多少元？
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">50 * (4/5)</gadget>
<output>40</output>

<gadget id="calculator">50 - 40</gadget>
<output>10</output>

<result>10</result>