A man buy a book in Rs50 & sale it Rs90. What is the rate of profit ???	Choose the correct choice from the following choices.
A) 10%
B) 80%
C) 30%
D) 25%
E) 28%
cp=50   sp=90   profit=90-50= 
<gadget id="calculator">90-50</gadget>
<output>40</output>
40   %=40/50*100= 
<gadget id="calculator">40/50*100</gadget>
<output>80</output>
80%   ANSWER:80%
<result>B</result>
A man buy a book in Rs50 & sale it Rs90. What is the rate of profit ???