A batch of apples arrives from the fruit shop. On the first day, you buy 30% of the apples. On the second day, you buy 120% of the first day, which is 30 kilograms more than the first day. How many kilograms are there in this batch of apples?
水果店运来一批苹果，第一天买了30%，第二天买的相当于第一天的120%，比第一天多买了30千克，这批苹果一共有多少千克？
<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">120 / 100</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">(3/10) * (6/5)</gadget>
<output>9/25 = around 0.36</output>

<gadget id="calculator">(9/25) - (3/10)</gadget>
<output>3/50 = around 0.06</output>

<gadget id="calculator">30 / (3/50)</gadget>
<output>500</output>

<result>500</result>