Mom goes to the flower shop to buy chrysanthemums, 16 yuan per pot, buy 3 pots and get 1 pot free, buy 3 pots at a time. How much is it cheaper per pot?
妈妈去花店买菊花，每盆16元，买3盆送1盆，一次买3盆．每盆便宜多少元？
<gadget id="calculator">16 * 3</gadget>
<output>48</output>

<gadget id="calculator">3 + 1</gadget>
<output>4</output>

<gadget id="calculator">48 / 4</gadget>
<output>12</output>

<gadget id="calculator">16 - 12</gadget>
<output>4</output>

<result>4</result>