The bookstore shipped a kind of children's storybook, sold 30% on the first day, and sold 120% of the first day on the second day, 30 more than the first day. How many children's story books did the bookstore ship in total?
书店运来一种儿童故事书，第一天卖了30%，第二天卖的相当于第一天的120%，比第一天多卖30本．书店一共运来多少本儿童故事书．
<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>