A bouquet of roses is 16 yuan, buy 3 bouquets and get one free, buy three bouquets at a time, how much is each bouquet cheaper?
玫瑰花16元一束，买3束送一束，一次买三束，每束便宜了多少元？
<gadget id="calculator">3 + 1</gadget>
<output>4</output>

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

<result>4</result>