Of 600 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 most appropriate option: A) 20 B) 25 C) 30 D) 35 E) 75
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; 600=1.25B+B-0.25B --&gt; B=300, A=1.25B= 375 and {Both}=0.25B=75.   The number of students who read only book A is {A}-{Both}=375-75= 
<gadget id="calculator">375-75</gadget>
<output>300</output>
300;   The number of students who read only book B is {B}-{Both}=300-75= 
<gadget id="calculator">300-75</gadget>
<output>225</output>
225;   The difference is  300-225= 
<gadget id="calculator"> 300-225</gadget>
<output>75</output>
75.   Answer: 75.
<result>E</result>
Of 600 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?