There are many situations that involve
increasing or decreasing an amount by a certain percent. Check out
the following examples:
1.

You normally work at the
mall over the spring break for $450. This year the
boss tells you that you will be receiving a 7% raise.
How much of an increase will you be receiving? How
much will you be earning in total this year? 

Solution: 
Your raise is
7% of your old salary.
Let r =
your raise
r = 7% • 450
r = 0.07 • 450
changing 7% to a decimal
r = 31.5
Your raise will be $31.50.
Your total earnings will be $450 + $31.50
which equals $481.50.


2.

Your dream CD player is
on sale for 20% off the original price. If the
original price is $270, what is the sale price? 

Solution: 
First, we will find the amount of
the discount.
The
discount = 20% of original price.
Let x =
the
discount.
x = 20% • 270
x = 0.20 • 270
x = 54
The discount is $54.
Now, the
sale price will be $270  $54
which equals $216 for the sale price.


3. 
The enrollment at a local elementary
school had 560 students last year. This year the
enrollment has decreased by 48 students. What is
the percent of decrease to the nearest tenth of a
percent? 

Solution: 
The enrollment
decrease = the percent of decrease of 560.
Let x = percent of
decrease
Answer to nearest tenth of a percent: 8.6%


