Adding & Subtracting Integers Review

ADDING

1

(−5)+8+(−3)+4  

(-5)+8 --> 8-5 = 3
3+(-3) = 0
0 + 4 = 4

2

12+(−7)+5+(−2)

12+(-7) --> 12-7 = 5
5+5 = 10
10+(-2) --> 10-2 = 8

3

(−10)+6+(−4)+9

(-10)+6 --> 10-6 = 4 --> (-4)

(-4)+(-4) = (-8)
-8+9 --> 9-8 = 1

4

3+(−5)+7+(−2)

3+(-5) --> 5-3 = 2 --> -2
(-2)+7 --> 7-2 = 5
5+(-2) --> 5-2 = 3

5

(−2)+4+(−6)+5

(-2)+4 --> 4-2 = 2
2+(-6) --> 6-2 = 4 --> -4
(-4)+5 --> 5-4 = 1

SUBTRACTING

1

6−3−4+(−2)

6−3=3
3−4=−1
−1+(−2)= −3
 

2

−5−(−3)−2+6

-5-(-3) --> -5+3 = -2
-2-2 --> -2+-2 = -4
-4+6 --> 6-4 = 2

3

10−8−(−5)+4

10−8 = 2
2-(-5) --> 2+5 = 7
7+4  = 11

4

(−7)−2−1+(−3)

-7-2 --> -7+(-2) = -9
-9-1 --> -9+(-1) = -10
-10+(-3) = -13

5

4−6−(−1)+5

4-6 --> 4 + (-6) --> 6-4 = 2 --> -2
-2 -(-1) --> -2 + 1 = -1
-1 + 5 = 4

WORD PROBLEMS

1

A temperature dropped from 15^∘C to 5^∘C overnight. Then, the temperature rose by 8^∘C during the day. What is the final temperature?

15−5+8 = 18^∘C

2

John has 20 dollars. He spends 7 dollars on lunch and then receives 5 dollars from his friend. How much money does John have now?

20−7+5 = 18 dollars

3

A swimmer swam 30 meters in the first lap, then swam back 12 meters, and finally swam another 20 meters forward. How far is the swimmer from the starting point?

30−12+20 = 38 meters

4

Emma has 50 stickers. She gives away 15 stickers to her classmates and then finds 8 more stickers at home. How many stickers does Emma have now?

50−15+8 = 43 stickers

5

A hiker starts a trail with 25 liters of water. During the hike, he drinks 10 liters and later fills up his bottle with 5 liters at a stream. How much water does the hiker have left?

25−10+5 = 20 liters

WHAT'S WRONG WITH THIS ANSWER?

1

Question: (-5) + 3 + (-2) + 4

Answer: (-5) + 3 + (-2) + 4 = 4

(-5) + 3 = (-2)
(-2) - 2 = 0
0 + 4 = 4

(-2) - 2 does not = 0, it = (-4), so the answer is 0

-5 + 3 = -2
-2 + -2 = -4
-4 + 4 = 0
(-5) + 3 + (-2) + 4 = 0

2

Question: 4 - (-14) 

Answer: 4 - (-14) = -10
4+(-14) --> 14 - 4 = 10 --> -10

Forgot to switch the sign on -14 to +14
4 + 14 = 18 

3

-3+2-(-4) = 5
-3 + 2 = 1
1 - (-4) --> 1 + 4 = 5

-3 + 2 is -1 not 1, so
-3 + 2 = -1
-1 - (-4) --> -1 + 4 = 3

4

Question: (-2) - 3 - 1 + 5 + 7

Answer: (-2) - 3 - 1 + 5 + 7 = 12
(-2)-3 --> -2 + 3 = 1
1 - 1 = 0
0 + 5 + 7 = 12

Forgot to change -3 to +3

(-2) - 3 --> (-2) + (-3) = (-5)
(-5) - 1 --> (-5) + (-1) = (-6)
(-6) + 5 = (-1)
(-1) + 7 = 6

5

Question: 10 + (-12) - 12

Answer: 10 + (-12) - 12 = 14

(-12) + (-12)  = (-24)
10 + (-24) --> 24 - 10 = 14 --> 14

Forgot to add the - back to 14 after 10 + (-24)

10 + (-24) --> 24 - 10 = 14 --> (-14)