I bought a book for Rs 60 , I sold off to a friend for Rs 70 but after a while i felt sorry , that i sold it and bought it back for Rs 80, how much loss did I incur?  Choose the correct option
A) 10 B) 15 C) 20 D) 25 E) 30
profit 70-60= 
<gadget id="calculator">70-60</gadget>
<output>10</output>
10   b p=80-60= 
<gadget id="calculator">80-60</gadget>
<output>20</output>
20   20-10= 
<gadget id="calculator">20-10</gadget>
<output>10</output>
10 loss.   10NSWER:10
<result>A</result>
I bought a book for Rs 60 , I sold off to a friend for Rs 70 but after a while i felt sorry , that i sold it and bought it back for Rs 80, how much loss did I incur?