There are 5,400 technical textbooks and story books; there are fewer technical books than story books (1/5); some technical books are shipped in, and the ratio of technical books to story books is 9:10. How many technical books are shipped?
科技科书和故事书共有5400本；科技书比故事书少(1/5)；又运来一些科技书，科技书与故事书的比是9：10，又运来多少本科技书？
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 + (4/5)</gadget>
<output>9/5 = around 1.8</output>

<gadget id="calculator">5_400 / (9/5)</gadget>
<output>3_000</output>

<gadget id="calculator">9 / 10</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">3_000 * (9/10)</gadget>
<output>2_700</output>

<gadget id="calculator">5_400 - 3_000</gadget>
<output>2_400</output>

<gadget id="calculator">2_700 - 2_400</gadget>
<output>300</output>

<result>300</result>