Books in a science and technology bookstore sold (3/10) of the total, and sold (1/10) and 90 copies of the total, and then shipped back 1200 books. At this time, the number of books in the science and technology bookstore was more than before (1 /5), how many books does this technology bookstore have?
某科技书店的书，卖出总数的(3/10)，又卖出总数的(1/10)又90册，后又新运回书1200册，这时科技书店的书比原来多(1/5)，该科技书店现有书多少册？
<gadget id="calculator">1_200 - 90</gadget>
<output>1_110</output>

<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

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

<gadget id="calculator">(3/10) + (1/10) + 1 + (-4/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1_110 / (3/5)</gadget>
<output>1_850</output>

<gadget id="calculator">1 + (1/5)</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">1_850 * (6/5)</gadget>
<output>2_220</output>

<result>2_220</result>