Honghong’s family buys saplings, the original price of each sapling is 20 yuan, now there is a promotion, buy 4 get 1 free, Honghong buys 5 at a time, how much is each sapling cheaper?
红红家买树苗，每棵树苗原价是20元，现在促销，买4送1，红红一次买5棵，每棵便宜多少钱？
<gadget id="calculator">20 * 4</gadget>
<output>80</output>

<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<gadget id="calculator">80 / 5</gadget>
<output>16</output>

<gadget id="calculator">20 - 16</gadget>
<output>4</output>

<result>4</result>