The school library bought a batch of new books, science books accounted for (1/5), and story books accounted for (7/20). It is known that there are 450 more story books than science books. How many new books are there in this batch? (solution with equation)
学校图书馆买来一批新书，科技书占(1/5)，故事书占(7/20)，已知故事书比科技书多450本，这批新书共有多少本？(用方程解答)
<gadget id="calculator">7 / 20</gadget>
<output>7/20 = around 0.35</output>

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

<gadget id="calculator">(7/20) - (1/5)</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">450 / (3/20)</gadget>
<output>3_000</output>

<result>3_000</result>