If I lost 40%, or 40 cents on the dollar, I received only 60 cents for every dollar the wagon cost; hence, it cost as many dollars as .60 is contained times in 51.00, which is 85.
Proof: 40% of $85 (85 × .40) = $34; $85 - $34 = $51.
Note.—The principles of percentage, in one form or another, enter into nearly all commercial calculations, besides many others. It is therefore of the utmost importance to business men, clerks, accountants, bookkeepers, and others, to become expert in percentage, and to adopt the easiest, simplest and shortest methods in computing interest, partial payments, trade discount, profit and loss, commission, insurance, stocks, bonds, taxes, exchange, etc.
PROFIT AND LOSS
When a thing is sold for more than it cost the seller, it is said to be sold at a profit. If it is sold for less than the cost, it is sold at a loss. Hence,
| Profit | = | Selling Price | - | Cost Price. |
| Loss | = | Cost Price | - | Selling Price. |
A profit or loss is generally reckoned as a percentage.
It is always understood that the percentage is reckoned on the cost price.
Example: I buy wheat at 60 cents and sell it for 75 cents. What per cent do I gain?
Solution: I gain the difference between 75 cents and 60 cents, or 15 cents. 15 cents is 25% of the cost. Hence, I gain 25%.