## Key Concepts

• Solve an application.
1. Identify what you are asked to find and choose a variable to represent it.
2. Write a sentence that gives the information to find it.
3. Translate the sentence into an equation.
4. Solve the equation using good algebra techniques.
5. Write a complete sentence that answers the question.
6. Check the answer in the problem and make sure it makes sense.
• Find percent increase.
1. Find the amount of increase:$\text{increase}=\text{new amount}-\text{original amount}$
2. Find the percent increase as a percent of the original amount.
• Find percent decrease.
1. Find the amount of decrease.$\text{decrease}=\text{original amount}-\text{new amount}$
2. Find the percent decrease as a percent of the original amount.

## Glossary

percent increase
The percent increase is the percent the amount of increase is of the original amount.
percent decrease
The percent decrease is the percent the amount of decrease is of the original amount.