Want Want gift packs are priced at 40 yuan per pack. Now we are holding a "buy four get one free" campaign. If you buy 4 packs, how much is each pack cheaper than before?
旺旺大礼包每包售价40元，现举行"买四送一"活动，如果买4包，每包比原来便宜多少钱？
<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">40 * (4/5)</gadget>
<output>32</output>

<gadget id="calculator">40 - 32</gadget>
<output>8</output>

<result>8</result>