<PRE><B>Question 1187631</B>
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The number of earth science books is 40% of 2500.


The number of Physics books is 5% of 2500.



These questions are of the &amp;nbsp;&quot; 2 x 2 = 4 &quot; &amp;nbsp;level of complexity.


It is the level of an advanced alumni of a kindergarten.



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If you need very introductory knowledge on percentage, look into the link

&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;- &lt;A HREF=http://www.algebra.com/algebra/homework/percentage/lessons/Percentage-problems.lesson&gt;Percentage problems&lt;/A&gt;

in this site.



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