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
