The C.P of 15 books is equal to the S.P of 19 books. Find his gain% or loss%?  Choose one.
A) 16 2/3%	B) 16 2/8%	C) 16 2/5%	D) 21 1/19%	E) 16 1/3%
15 CP = 19 SP   19 --- 4 CP loss   100 --- ? =&gt; 21 1/19% loss.Answer: 21 1/19%
<result>D</result>
The C.P of 15 books is equal to the S.P of 19 books. Find his gain% or loss%?