The amount and rate given, to find the base.
Rule.—Divide the given amount by 1.00 plus the rate per cent.
Example: Bought a horse at a certain price, and sold him for $84, making 12% on cost; what did he cost?
| 1.12 | ) | 84.00 |
| Ans. $75 | ||
If I made 12% on cost, every dollar invested gained 12 cents; hence, the horse cost as many dollars as 1.12 is contained times in 84.00, which is 75.
Proof: 12% of $75 (75 × .12) = $9; $75 + $9 = $84.
The proceeds and the rate given, to find the base.
Rule.—Divide the given proceeds by 1.00 minus the rate per cent.
Example: Sold a wagon for $51, which is 40% less than it cost; what did it cost?
| .60 | ) | 51.00 |
| Ans. $85 | ||