How do you calculcate a percentage decrease?

Answer 1

First find the percentage of a number:

a/b = p/100, *P is the percentage

Here is a sample problem:

What is %40 of 50?

You would write that as:

a/50 = 40/100

Simplify (When possible)

a/50 = 2/5

Convert:

How many times does it take 5 to go into 50?

a/50 = 2x10/5x10

Answer: 10

a/50 = 20/50

Divide (by 50)

a = 20

20 is %40 of 50

Then find increase or decrease:

Sample problem: 100 to 50 (decrease) *remember: a/b = p/100

We are trying to find p so the equation is:

50/100 = p/100

Multiply by 100 to get p by itself

50 = p

Answer: The percentage of decrease is 50 percent

Sample problem: 256 to 224 (decrease) *remember: a/b = p/100

We are trying to find p so the equation is:

224/256 = p/100

Simplify (When possible)

.875 = p/100

Multiply by 100 to get p by itself

87.5 = p

Answer: The percentage of decrease is 87.5 percent