The school distributes 300 books to three classes of the sixth grade. Class 1 is assigned to (1/4), Class 2 is assigned to (2/5), and the rest is assigned to Class 3. How many books are assigned to Class 3?
学校将300本图书分给六年级三个班，1班分到(1/4)，2班分到(2/5)，剩下的分给3班，3班分到多少本？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

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

<gadget id="calculator">1 - (1/4) - (2/5)</gadget>
<output>7/20 = around 0.35</output>

<gadget id="calculator">300 * (7/20)</gadget>
<output>105</output>

<result>105</result>