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LESSON 5-5
Warm Up
ALGEBRA READINESS
LESSON 5-5
Warm Up
The youngest major
league baseball player of
all time was only 15 when
he began his career in
1944 Who was he? To
find out, evaluate each
expression in a row for
the given value, n. Circle
the letter of the algebraic
expression with the
lowest value. Then, write
the letter in the s[ace
above the problem
number in the code box
below.
ALGEBRA READINESS
“Solving Equations by Adding or
Subtracting” (5-5)
How do you
solve equations
in that involve
adding or
subtracting
fractions?
Solving equations with fractions is just like solving equations with any rational
numbers. You need to isolate the variable by undoing the addition and / or
subtraction operations using the Addition and Subtraction Properties of Equality.
1
Example: During the first week of January, a rain gauge collected 2 in. of rain. By the
end of January, the total rainfall was 2 58 in. How much rain fell after the first week in
January?
ALGEBRA READINESS
Solving Equations by Adding or Subtracting
LESSON 5-5
Additional Examples
Solve x – 1 = 3 .
8
x–
4
1
3
1
+ 8 = +1
4
8
8
Addition Property of Equality
3
1
+
4
8
Inverse Property of Addition
x+0 =
6
1
x= 8+ 8
The LCD is 8. Write 3 as 6 .
x=7
Add.
8
4
8
ALGEBRA READINESS
Solving Equations by Adding or Subtracting
LESSON 5-5
Additional Examples
An empty container weighs 1 lb.
12
The same container full of chopped fruit weighs 7 lb.
8
How much does the fruit weigh?
Words
weight of
+
empty container
weight of
fruit
=
weight of
full container
=
7
8
Let f = the weight of the fruit.
Equation
1
12
+
f
ALGEBRA READINESS
Solving Equations by Adding or Subtracting
LESSON 5-5
Additional Examples
(continued)
1
1
+f – 1 = 7 –
12
8 12
12
f+0= 7 – 1
8
12
= 21 – 2
24
=
19
24
24
Subtraction Property of Equality
Inverse Property of Addition
The LCD is 24. Write each fraction
with a denominator of 24.
Subtract.
The weight of the fruit is 19 lb.
24
ALGEBRA READINESS
Solving Equations by Adding or Subtracting
LESSON 5-5
Lesson Quiz
Solve each equation.
1. x + 1 = 14
2. x + 10 5 = 16 1
3. 17 3 + x = 18 1
4. x – 9 = 3 7
3
x= 3
5
4
15
8
x=55
8
12
x= 1
3
10
3
x=4
5
4
10
ALGEBRA READINESS