There is a batch of watermelons in the fruit shop. After selling (2/5), there are 180 kilograms left. How many kilograms is this batch of watermelon?
水果店有一批西瓜，卖出(2/5)后，还剩180千克．这批西瓜有多少千克？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">180 / (3/5)</gadget>
<output>300</output>

<result>300</result>