### Percent Equations

The percent equation is often used to solve problems. It goes like this:

** Rate** is the ratio that the percent represents (

** Total** is often called the

**.**

*base unit*** Part** is the amount we are comparing with the base unit.

#### Finding a Percent of a Total

Find 25% of $80.

We are looking for the ** part**. The

**is $80. ‘of’ means multiply.**

*total***$20**.

#### Expression Values and Percentages

Express $90 as a percentage of $160.

This time we are looking for the ** rate**. We are given the

**($90) and the**

*part***($160). Using the rate equation, we get**

*total*#### Finding the Total Sum

$50 is 15% of what total sum?

This time we are looking for the ** total**. We are given the

**($50) and the**

*part***(15%, or 0.15). Using the rate equation, we get**

*rate***$50 is 15% of $333.33.**

### Example

#### Example 1

$96 is 12% of what total sum?

This time we are looking for the ** total**. We are given the

**($96) and the**

*part***(12%, or 0.12). Using the rate equation, we get**

*rate***$96 is 12% of $800.**

### Review

Find the following.

- 30% of 90
- 27% of 19
- 16.7% of 199
- 11.5% of 10.01
- 0.003% of 1,217.46
- 250% of 67
- 34.5% of y
- 17.02% of y
- x% of 280
- a% of 0.332
y% of3x

### Review (Answers)

To view the Review answers, open this PDF file and look for section 3.14.

### Texas Instruments Resources

*In the CK-12 Texas Instruments Algebra I FlexBook® resource, there are graphing calculator activities designed to supplement the objectives for some of the lessons in this chapter. See http://www.ck12.org/flexr/chapter/9613.*