The school library has purchased 300 books, and science and technology books accounted for (7/12) of the total books purchased in the mid-term. Among the science and technology books, science fiction books accounted for (3/7). , How many science fiction books are there?
学校图书馆购买了300册图书，期中科技类图书占所购图书总量的(7/12)，在科技类图书中，科幻类又占了(3/7)，则这次购买的图书中，科幻类图书有多少本．
<gadget id="calculator">7 / 12</gadget>
<output>7/12 = around 0.583333</output>

<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">300 * (7/12) * (3/7)</gadget>
<output>75</output>

<result>75</result>