Example 2: The fruit store shipped some apples, sold 20% on the first day, and sold 150% of the first day on the second day. At this time, there are 300 kilograms left. How many kilograms of apples were shipped in total?
例2：水果店运来一些苹果，第一天卖了20%，第二天卖的相当于第一天卖的150%，这时还剩300千克，求一共运来多少千克苹果？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">150 / 100</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">(1/5) * (3/2)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">1 - (1/5) - (3/10)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">300 / (1/2)</gadget>
<output>600</output>

<result>600</result>