Addition equations

2-5 Addition Equations

Warm Up
Problem of the Day
Lesson Presentation

Course 1
Course 1
Course 1


Warm Up
Determine whether each value is a solution.

1. 86 + x = 102 for x = 16 yes

2. 18 + x = 26 for x = 4 no
3. x + 46 = 214 for x = 168 yes
4. 9 + x = 35 for x = 26 yes

Course 1


Problem of the Day
After Renee used 40 m of string for her kite
and gave 5 m to her sister for her wagon,
she had 8 m of string left. How much string
did she have to start with?
53 m

Course 1


Learn to solve whole-number addition
equations.

Course 1


h + 14 82
The equation h + 14 = 82 can be
represented as a balanced scale.

h ?
To find the value of h, you need h
by itself on one side of the scale.

h + 14
82 To get h by itself, first take away
14 from the left side of the scale.
Now the scale is unbalanced.

h 68
To rebalance the scale, take away
14 from the other side.

Course 1


Taking away 14 from both sides of the scale is
the same as subtracting 14 from both sides of
the equation.

h + 14 = 82
–14 –14
h = 68

Subtraction is the inverse, or opposite, of
addition. If an equation contains addition,
solve it by subtracting from both sides to
“undo” the addition.

Course 1


Additional Example 1A: Solving Addition Equations
Solve the equation. Check your answer.
x + 87 = 152

x + 87 = 152 87 is added to x.
– 87 – 87 Subtract 87 from both sides
x = 65 to undo the addition.

Check x + 87 = 152 Substitute 65 for x in the
?
65 + 87 = 152 equation.
?
152 = 152  65 is the solution.

Course 1


Additional Example 1B: Solving Addition Equations
72 = 18 + y

72 = 18 + y 18 is added to y.
–18 –18 Subtract 18 from both sides
54 = y to undo the addition.

Check 72 = 18 + y Substitute 54 for y in the
?
72 = 18 + 54 equation.
?

Course 1


Check It Out: Example 1A
u + 43 = 78
u + 43 = 78 43 is added to u.
– 43 – 43 Subtract 43 from both sides
u = 35 to undo the addition.

Check u + 43 = 78 Substitute 35 for u in the
?
35 + 43 = 78 equation.
?

Course 1


Check It Out: Example 1B
68 = 24 + g
68 = 24 + g 24 is added to g.
–24 –24 Subtract 24 from both sides
44 = g to undo the addition.

Check 68 = 24 + g Substitute 44 for g in the
?
68 = 24 + 44 equation.
?

Course 1

Additional Example 2: Social Studies Application
Johnstown, Cooperstown, and Springfield are located
in that order in a straight line along a highway. It is
12 miles from Johnstown to Cooperstown and 95
miles from Johnstown to Springfield. Find the distance
d between Cooperstown and Springfield.

distance between distance between distance between
Johnstown and = Johnstown and + Cooperstown and
Springfield Cooperstown Springfield

95 = 12 + d
95 = 12 + d 12 is added to d.
–12 –12 Subtract 12 from both sides to undo
the addition.
83 = d
It is 83 miles from Cooperstown to Springfield.
Course 1

Check It Out: Example 2
Patterson, Jacobsville, and East Valley are located in
that order in a straight line along a highway. It is 17
miles from Patterson to Jacobsville and 35 miles from
Patterson to East Valley. Find the distance d between
Jacobsville and East Valley.

distance between distance between distance between
Patterson and East = Patterson and + Jacobsville and
Valley Jacobsville East Valley
35 = 17 + d
35 = 17 + d 17 is added to d.

–17 –17 Subtract 17 from both sides to
undo the addition.
18 = d
It is 18 miles from Jacobsville to East Valley.
Course 1


Lesson Quiz

Solve each equation.

1. x + 15 = 72 x = 57

2. 81 = x + 24 x = 57

3. x + 22 = 67 x = 45

4. 93 = x + 14 x = 79

5. Kaitlin is 2 inches taller than Reba. Reba is 54
inches tall. How tall is Kaitlin?
56 inches

Course 1

Addition equations

More Related Content

What's hot (19)

Similar to Addition equations (20)

More from Ms. Jones (20)

Addition equations