Of 440 surveyed students, 20% of those who read book A also read book B and 25% of those who read book B also read book A. If each student read at least one of the books, what is the difference between the number of students who read only book A and the number of students who read only book B? Choose the correct choice from the following:
A) 20 B) 25 C) 30 D) 35 E) 55
Say the number of students who read book A is A and the number of students who read book B is B.   Given that 20% of those who read book A also read book B and 25% of those who read book B also read book A, so the number of students who read both books is 0.2A=0.25B --&gt; A=1.25B.   Since each student read at least one of the books then {total}={A}+{B}-{Both} --&gt; 440=1.25B+B-0.25B --&gt; B=220, A=1.25B=275 and {Both}=0.25B=55.   The number of students who read only book A is {A}-{Both}=125-25= 
<gadget id="calculator">125-25</gadget>
<output>100</output>
100;   The number of students who read only book B is {B}-{Both}=275-55-220;   The difference is  220-55= 
<gadget id="calculator"> 220-55</gadget>
<output>165</output>
165.   Answer:55.
<result>E</result>
Of 440 surveyed students, 20% of those who read book A also read book B and 25% of those who read book B also read book A. If each student read at least one of the books, what is the difference between the number of students who read only book A and the number of students who read only book B?