basketball is 35 yuan, and the store has an event, buy 4 get 1 free, Mr. Wang buys back 5, how much can each be cheaper?
一个篮球35元，商店做活动，买4送1，王老师买回5个，每个可以便宜多少钱？
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">35 * (4/5)</gadget>
<output>28</output>

<gadget id="calculator">35 - 28</gadget>
<output>7</output>

<result>7</result>