1. Warm Up
Graph each number on a number line.
1. –
3. –
–5 –4 –3 –2 –

2. Example 1: Using a Number Line to Add Integers
Use a number line to find the sum.
A. (–6) + 2 –6 2
–6 –5 –4 –3 –2 –
You finish at –4, so (–6) + 2 = –4.
To add a positive number move to the right. To add a negative number move to the left.
Helpful Hint

3. Example 1: Using a Number Line to Add Integers
Use a number line to find the sum.
B. –3 + (–6) –6 –3
–9 –8 –7 –6 –5 –4 –3 –2 –
You finish at –9, so –3 + (–6) = –9.

4. –6 –5 –4 –3 –2 –1 0 1 2 3 4 5 Check It Out: Example 1
Use a number line to find the sum.
A. (–3) + 7 –3 7
–6 –5 –4 –3 –2 –
You finish at 4, so (–3) + 7 = 4.

5. –6 –5 –4 –3 –2 –1 0 1 2 3 4 5 Check It Out: Example 1
Use a number line to find the sum.
B. (–2) + 4 –2 4
–6 –5 –4 –3 –2 –
You finish at 2, so (–2) + 4 = 2.

7. Example 2: Using Absolute Value to Add Integers
C. (–2) + (–4)
B. (–8) + 5
1 + (–2)
(–8) + 5
(–2) + (–4) –1 –3 –6

8. Check It Out: Example 2
Add.
A. 3 + (–6)
B. (–4) + 1
C. (–6) + (–7)
3 + (–6)
(–4) + 1
(–6) + (–7) –3 –3
–13

9. Example 3: Evaluating Expressions with Integers
Evaluate for the given variable.
A. c + 4 for c = –8.
B. d + 7 for d = –3.
c + 4
d + 7
(–8) + 4
(–3) + 7
–8 + 4 = –4
–3 + 7 = 4

10. Example 4: Application
Meka opened a new bank account. Find her account balance after the first four transactions listed below.
Deposits: $200, $20 Withdrawals: $166, $38
Use a positive sign for deposits and a negative sign for withdrawals.
(–166) + (–38)
Use the Associative Property to group integers with same signs.
( ) + (–166 + –38)
220 + (–204)
Add integers within each group. 16
220 > 204; use the sign of 220.
Meka’s account balance after the first four transactions is $16.

11. Check It Out: Example 4
Michael opened a new bank account. Find his account balance after the first four transactions listed below.
Deposits: $175, $95 Withdrawals: $133, $65
Use a positive sign for deposits and a negative sign for withdrawals.
(–133) + (–65)
( ) + (–133 + –65)
Use the Associative Property to group integers with same signs.
270 + (–198)
Add integers within each group. 72
270 > 198; use the sign of 270.
Michael’s account balance after the first four transactions is $72.

12. Lesson Quiz
Add.
1. –7 + (– 7) (–9) + (–2)
–14 4
Evaluate each expression for the given value of the variable.
r for r = – b + (–9) for b = –6 –2
–13
5. On Monday, a local dog shelter had six dogs. By Friday they had found homes for three, but took in two more. Then how many dogs were in the shelter?
5 dogs