Jiajiale Supermarket is running a promotional activity. Each pack of milk powder is 78 yuan. Buy 4 get 1 free. Lili’s mother bought 4 packs. How much is each pack cheaper?
家家乐超市搞促销活动，奶粉每包78元，买4送1，丽丽的妈妈买了4包，每包便宜了多少钱？
<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">78 * (4/5)</gadget>
<output>312/5 = around 62.4</output>

<gadget id="calculator">78 - (312/5)</gadget>
<output>78/5 = around 15.6</output>

<result>78/5 = around 15.6</result>