Adding and Subtracting with Like Denominators

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Adding and Subtracting with Like Denominators
4-8
Warm Up
Problem of the Day
Lesson Presentation
Course 1
2
Warm Up Write each mixed number as an improper
fraction. 1. 6 2. 2 3. 3 4. 8 5.
9 6. 4
3
Problem of the Day Marge has six coins that
total 1.15. She cannot make change for 1.00, a
half-dollar, a quarter, a dime, or a nickel. What
coins does she have?
half dollar, quarter, 4 dimes
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Learn to add and subtract fractions with like
denominators.
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Additional Example 1 Application
Snow was falling at a rate of inch per hour.
How much snow fell after two hours? Write your
answer in simplest form.

Add the numerators. Keep the same denominator.


Write your answer in simplest terms.



After 2 hours inch of snow fell
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Try This Example 1
Rain was falling at a rate of inch per hour.
How much rain fell after two hours? Write
your answer in simplest form.

Add the numerators. Keep the same denominator.


Write your answer in simplest terms.



After 2 hours inch of rain fell.
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Additional Example 2A Subtracting Like Fractions
and Mixed Numbers Subtract. Write the answer in
simplest form. A. 1
To get a common denominator, rewrite 1 as a
fraction with a denominator of 5.

Subtract the numerators. Keep the same
denominator.

?

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Additional Example 2B Subtracting Like Fractions
and Mixed Numbers Subtract. Write the answer in
simplest form. B. 5 2
2

Subtract the fractions.
5
Then subtract the whole numbers.
3
3
Write your answer in simplest form.
-

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Try This Example 2A Subtract. Write the answer
in simplest form. A. 1
To get a common denominator, rewrite 1 as a
fraction with a denominator of 6.

Subtract the numerators. Keep the same
denominator.



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Try This Example 2B
Subtract. Write the answer in simplest form. B.
4 2

Subtract the fractions.
4
2
Then subtract the whole numbers.
2
2
Write your answer in simplest form.
-

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Additional Example 3A Evaluating Expressions
with Fractions
Evaluate the expression for x . Write each
answer in simplest form.

x
A.
x

Write the expression.
Substitute for x and subtract the
numerators. Keep the same denominator.


Write your answer in simplest form.

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Additional Example 3B Evaluating Expressions
with Fractions
Evaluate the expression for x . Write each
answer in simplest form.
B.

x
2

x
Write the expression.
2
Substitute for x. Add the fractions. Then add
the whole numbers.
2


2
Write your answer in simplest form.
2

, or
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Additional Example 3C Evaluating Expressions
with Fractions
Evaluate the expression for x . Write each
answer in simplest form.
C.

x

x
Write the expression.
Substitute for x and add the numerators. Keep
the same denominator.


1
, or
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Try This Example 3A Evaluate the expression for
x . Write each answer in simplest form.

x
A.
x

Write the expression.

Substitute for x and subtract the numerators.
Keep the same denominator.

Write your answer in simplest form.

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Try This Example 3B Evaluate the expression for
x . Write each answer in simplest form.
B.

x
3

x
Write the expression.
3
Substitute for x and add the numerators.
Keep the same denominator.
3


3
Write your answer in simplest form.
3

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Try This Example 3C Evaluate the expression for
x . Write each answer in simplest form.
C.

x

x
Write the expression.
Substitute for x and add the numerators.
Keep the same denominator.


1
, or
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Lesson Quiz
Add or subtract. Write each answer in simplest
form. 1. 1 2. 1 4. Evaluate x
for x .
3. 2 4
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5. Weston walks of a mile every day. How far
will he have walked in 4 days?
3 miles