I sold a book at a profit of 10%. Had I sold it for $90 more, 15% would have been gained. Find the cost price?	Choose the correct choice from the following answers:	A) $1800	B) $2500	C) $3000	D) $3120	E) $1540
115% of cost - 110% of cost = $90   5% of cost = $90   cost = 90*100/5= 
<gadget id="calculator">90*100/5</gadget>
<output>1_800</output>
$1800   $1800nswer is $1800
<result>A</result>
I sold a book at a profit of 10%. Had I sold it for $90 more, 15% would have been gained. Find the cost price?