Download Percent Equations - Solon City Schools

We are learning to…solve for the part, total or percent
using an equation.
Wednesday, May 24, 2017
Review
 With your group review how to solve for parts, totals
and percents by using your proportional reasoning.
 When you’re done raise your hand and have your
teacher check your solutions.
Review
%
 To write a percent as a fraction you always write:
100
 A percent is always a comparison out of 100.
 To write a fraction as a decimal you divide the numerator by the
denominator.
 To write the percent as a decimal you would divide the percent by 100.
68
 For example: 68% as a fraction would be…
100
then to write 68% as a decimal: 68 100  0.68
 Write the percents found in your notes as decimals.
 As you work look for short cuts when writing a percent as a
decimal.
Percents as a proportion: Using a proportion
we know that:
Percent Equations
Parts
Totals
Part
Total
Percent
100
percent part
=
100
total
and we also know that the percent divided by 100 is the way to write the percent as a decimal
percent as a decimal 
part
total
If I wanted to solve for the part then I would multiply both sides of the equation by the total…
percent as a decimal  total 
part
 total
total
percent as a decimal  total  part
Here is an equation that we can use to solve for parts, totals and percents instead of
using the proportion!
Practice
Question
What number is 10%
of 90?
15 is 30% of what
number?
What percent is 2 of
20?
Define the
variable
Equation and Solution Process
Solution
x = part
percent as decimal • total = part
0.1 • 90 = x
9
x = total
percent as decimal • total = part
0.3 x = 15
50
0.3
x = percent
0.3
percent as decimal • total = part
20x = 2
20
20
0.1 =
10%
Group Practice
 Try the rest of the practice problems with your group.
 Be sure to define the variable before you set up the
equation!