I sold a book at a profit of 10%. Had I sold it for $140 more, 15% would have been gained. Find the cost price?	Choose one:
A) $2000
B) $2500
C) $3000
D) $2800
E) $1540
115% of cost - 110% of cost = $140   5% of cost = $140   cost = 140*100/5= 
<gadget id="calculator">140*100/5</gadget>
<output>2_800</output>
$2800   Answer is $2800
<result>D</result>
I sold a book at a profit of 10%. Had I sold it for $140 more, 15% would have been gained. Find the cost price?