There are a total of 3,000 science and story books in the school library, of which science books account for (2/5). Because the students like to read science books, they bought some more. At this time, science books account for (3/5) of the total. The school How many technical books did you buy later?
学校图书馆有科技书和故事书一共3000本，其中科技书占(2/5)，由于同学们喜欢看科技书，又买来一些，这时科技书占总数的(3/5)，学校后来买来多少本科技书？
<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">3_000 * (3/5)</gadget>
<output>1_800</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">3_000 * (2/5)</gadget>
<output>1_200</output>

<gadget id="calculator">3_000 - 3_000 - 1_200</gadget>
<output>-1_200</output>

<gadget id="calculator">1_800 + (-1_200)</gadget>
<output>600</output>

<gadget id="calculator">1 - (3/5)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">600 / (2/5)</gadget>
<output>1_500</output>

<result>1_500</result>