fresh fruit store bought a batch of watermelons, sold 20% of them, and left 280 kilograms. How many kilograms were there in this batch of watermelons? (solution by equation)
鲜鲜水果店购进一批西瓜，卖了20%后，还剩280千克，这批西瓜原来有多少千克？(用方程解)
<gadget id="calculator">280 / 0.8</gadget>
<output>350</output>

<result>350</result>