There was a batch of storybooks in the school library. After the senior students borrowed them (2/5), the administrator bought another 180 storybooks from Xinhua Bookstore. At this time, the ratio of the number of storybooks to the original one is 3:4. How many storybooks were there originally?
学校图书室原有一批故事书，高年级学生借走(2/5)以后，管理员又从新华书店买来180本故事书．这时故事书的本数与原来的比是3：4，原来有故事书多少本？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

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

<gadget id="calculator">(3/4) - 1</gadget>
<output>-1/4 = around -0.25</output>

<gadget id="calculator">(2/5) + (-1/4)</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">180 / (3/20)</gadget>
<output>1_200</output>

<result>1_200</result>