Percent Problems

Solving Simple Percent Problems

Using the Percent Proportion

Simple percent problems have three parts.

1. The percentage – easy to spot – has %

2. The base – always follows the word “of”

3. The amount – the third number

Find 5% of 20

Identify the three parts.

1. The percentage – 5%2. The base – of 203. The amount – what we are trying to

find – x

The Percent Proportion

This proportion always works with simple percent problems.

100

amount percent

base

Find 5% of 20

1. The percentage – 5%2. The base – of 203. The amount – what we are trying to find – x

100

amount percent

base

5

20 100

x

Find 5% of 20

Cross-multiply: 100 x = 100 Divide: x = 1

5% of 20 is 1

100

amount percent

base 5

20 100

x

What percent of 40 is 15?

1. The percentage – what we are trying to find – x

2. The base – of 403. The amount – 15

100

amount percent

base

15

40 100

x

What percent of 40 is 15?

Cross-multiply: 40 x = 1500 Divide: x = 37.5

15 is 37.5% of 40

100

amount percent

base 15

40 100

x

20 is 40% of what number?

1. The percentage – 40% 2. The base – what we are trying to find - of what -

x3. The amount – 20

100

amount percent

base 20 40

100x

20 is 40% of what number?

Cross-multiply: 40 x = 2000Divide: x = 50

20 is 40% of 50

100

amount percent

base 20 40

100x

Using the Percent Proportion

The percentage – easy to spot – has %

The base – always follows the word “of”

The amount – the third number

To solve: Cross-multiply and divide

100

amount percent

base