During Mother's Day, Yangyang Flower Shop launched a promotion, 5 yuan per carnation, buy 4 carnations and get one free, buy 5 at a time, how much is each carnation cheaper?
母亲节期间，洋洋花店开展促销，每枝康乃馨5元，买4枝送一枝，一次买5枝，每枝便宜多少元？
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

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

<gadget id="calculator">5 - 4</gadget>
<output>1</output>

<result>1</result>