Cactus Bookstore, opening bonus, all books, buy four get one free, Mr. Zhang is going to buy 50 copies of "One Hundred Thousand Whys". It is known that each copy of "One Hundred Thousand Whys" is priced at 12 yuan. Do you know how much cheaper each book can be? money?
仙人掌书店，开业酬宾，全场图书，买四赠一，张老师准备买50本《十万个为什么》，已知《十万个为什么》每本售价12元，你知道每本可以便宜多少钱？
<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">12 * (4/5)</gadget>
<output>48/5 = around 9.6</output>

<gadget id="calculator">12 - (48/5)</gadget>
<output>12/5 = around 2.4</output>

<result>12/5 = around 2.4</result>