Aptitude :: Profit and Loss
IMPORTANT FACTS
Cost Price:
The price, at which an article is purchased, is called its cost price, abbreviated as C.P.
Selling Price:
The price, at which an article is sold, is called its selling prices, abbreviated as S.P.
Profit or Gain:
If S.P. is greater than C.P., the seller is said to have a profit or gain.
Loss:
If S.P. is less than C.P., the seller is said to have incurred a loss.
IMPORTANT FORMULAE

Gain = (S.P.)  (C.P.)

Loss = (C.P.)  (S.P.)

Loss or gain is always reckoned on C.P.

Gain Percentage: (Gain %)
Gain % = Gain x 100 C.P. 
Loss Percentage: (Loss %)
Loss % = Loss x 100 C.P. 
Selling Price: (S.P.)
SP = (100 + Gain %) x C.P 100 
Selling Price: (S.P.)
SP = (100  Loss %) x C.P. 100 
Cost Price: (C.P.)
C.P. = 100 x S.P. (100 + Gain %) 
Cost Price: (C.P.)
C.P. = 100 x S.P. (100  Loss %) 
If an article is sold at a gain of say 35%, then S.P. = 135% of C.P.

If an article is sold at a loss of say, 35% then S.P. = 65% of C.P.

When a person sells two similar items, one at a gain of say x%, and the other at a loss of x%, then the seller always incurs a loss given by:
Loss % = Common Loss and Gain % 2 = x 2 . 10 10 
If a trader professes to sell his goods at cost price, but uses false weights, then
Gain % = Error x 100 %. (True Value)  (Error)