One kind of flower is 160 yuan per pot, buy 3 pots and get one free. How much is it cheaper to buy 3 pots at a time?
一种花每盆160元，买3盆送一盆．一次买3盆，每盆便宜多少钱？
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">160 * (3/4)</gadget>
<output>120</output>

<gadget id="calculator">160 - 120</gadget>
<output>40</output>

<result>40</result>