Algebra 1 : How to find the percent of decrease
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Example Question #11 : How To Find The Percent Of Decrease
What is the percent decrease from 
To find the percent of decrease from one number to the next we use the formula:
In this case, the difference is
So our formula would be
From 
Example Question #11 : How To Find The Percent Of Decrease
For your 16th birthday, your parents have decided to help you buy a car. The car you want costs $2500. Your parents said they would contribute $700 toward the purchase price of the car. What was the percent decrease in the price you have to pay for the new car after their contribution?
To calculate the percent decrease in a price, quantity etc. you need to establish a ratio between the new and lower price and the old, higher price. Then convert to a percentage by multiplying by 100.
Establish a ratio between the new and the old:
Convert to a percentage:
So the parental discount amounts to 72% of the old price. In other words with their help, you will only pay 72% of the original price. Because you are now paying only 72% of that price, that was a decrease of 28% (100-72=28%).
Alternatively find the difference between the two prices, divide by the original price, and multiply by 100. Try this method to see that you get the SAME answer.
Example Question #13 : How To Find The Percent Of Decrease
Jimmy's magazine kiosk has seen a decline in sales for January. December sales totaled 
To find the percent of decrease, we take the difference in sales and divide that by the original sales income:
Example Question #14 : How To Find The Percent Of Decrease
Oscar brought 72 cookies to a company picnic. By picnic's end there were only 7 cookies left. By what percentage did Oscar's batch of cookies decrease?
To determine the percent of decrease, we must first find the difference between the initial and diminished counts and divide the difference by the initial value:
Next, we multiply the given value by 
Example Question #15 : How To Find The Percent Of Decrease
Charlie bought stock initially valued at 
First we want to get the total cash value of depreciation and divide that by the initial stock value:
To get the percent value of decrease, we then multiply the given decimal by 
Example Question #121 : Percent Of Change
Paul wanted to sell his car last year. At the time, he was fairly certain that his car was worth $15000. 1 year later, Paul has finally gotten around to selling his car. Unfortunately, due to depreciation in value, the car is only worth $12000. By what percent, did Paul’s car decrease in value?
Let 
Plug in the appropriate values into this expression.
Paul's car lost 20% of its value in 1 year.
Example Question #11 : How To Find The Percent Of Decrease
The cost of milk last week was $2.50 a gallon. This week, it is on sale for $2 a gallon. Find the percent of decrease.
To find the percent of decrease, we use the formula
So, we will substitute our values.
We get
Therefore, the percent decrease is 20%.
Example Question #18 : How To Find The Percent Of Decrease
Dr. Beverly Crusher is looking at how many patients she has treated over the last several years. She is interested to see how many patients have had the flu each year. She notices that last year she treated 
To find the percent decrease, we need to find how many less patients she has treated (the decrease). This is just taking the difference between the patients she treated last year and those she treated this year,
Now we can just divide this number by the total patients she treated last year to get a decimal,
To turn it into a percentage you just multiply it by
The formula to get the percent decrease is the decrease divided by the initial total, multiplied by
Example Question #19 : How To Find The Percent Of Decrease
Last week, the price of carrots at the farmer's market was 
To find percent decrease, we use the following formula:
So, if we substitute, we get
If we round to the nearest percent, we get 33%.
Example Question #12 : How To Find The Percent Of Decrease
A bag of candy has 200 pieces when opened. After eating some, there are 146 left. What is the percent decrease?
None of the other answers.
Find the amount of decrease, divide it by the starting number, and multiply by 100 to convert to a percentage.
A 27% decrease.
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