A fruit shop sells 40% of the total number of fruits on the first day, 3/4 of the first day on the second day, and all of them are sold out on the third day. It is known that the first day sold 50 kilograms more than the second day, how many kilograms are there in total for this batch of fruits?
水果店一批水果，第一天卖出总数的40%，第二天卖出第一天的(3/4)，第三天全部售完．已知第一天比第二天多卖50千克，求这批水果共有多少千克？
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">(2/5) * (3/4)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">(2/5) - (3/10)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">50 / (1/10)</gadget>
<output>500</output>

<result>500</result>