The yogurt in the store is 12.5 yuan per bag, buy 4 and get 1 free, how much is it actually per bag.
商店里的酸奶每袋12.5元，买4赠1，实际每袋多少元．
<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">12.5 * (4/5)</gadget>
<output>10</output>

<result>10</result>