Math 40
Prealgebra
Section 4.4 – HOMEWORK
In Exercises 1-26, perform the indicated operation.
1.
5  3
 
8  8
3.

5.
10 5

12 12
2.

4.
3 7

10 10
11 5

12 12
6.
3 7

8 8
7.
1 8
 
9 9
8.

9.

10.
13  6 
 
16  16 
11.
9 1

10 10
12.
3  1
  
5  5
13.
7  5
 
8  8
14.
2  7
 
9  9
15.
2  7
  
9  9
16.
7  5
  
8  8
17.
7  13 
 
18  18 
18.

19.
4  8
  
3  3
20.
1  13 
  
6  6
21.

22.

23.
6 13
 
5 5
24.
7 15

4 4
25.
3  9 
 
14  14 
26.

5  9 
 
16  16 
9 7

21 21
5  5
 
18  18 
8 9

15 15
7 27

30 30
3  11 
 
20  20 
7  7
 
15  15 
1
2015 Carreon
Math 40
Prealgebra
Section 4.4 – HOMEWORK
In Exercises 27-48, perform the indicated operation.
27.
3  9 
 
14  14 
28.

29.

15 11

4 4
30.
13 15

32 32
31.
13 19

32 32
32.

33.
7 2
 
x x
34.
1 9

u u
35.
a 5

10 10
36.
n 4

18 18
37.
1
1

2c 2c
38.
7
1

3x 3x
39.

40.

5
5

7a 7a
41.
5x
x

8m 8m
42.

7n n

16 16
43.

44.

6a  3 
 
5  5
45.
4 2a

3c 3c
46.
4a 2a

3c 3c
47.

48.
x x
 
4 4
3
9

4u 4u
6a  3a 
 
5  5 
x
x

2n 2n
7  7
 
15  15 
7  17 
 
18  18 
2
2015 Carreon
Math 40
Prealgebra
Section 4.4 – HOMEWORK
In Exercises 49-64, find the LCM by listing multiples of each number.
49.
9 and 15
50.
6 and 10
51.
12 and 8
52.
20 and 12
53.
6 and 9
54.
15 and 6
55.
20 and 8
56.
12 and 16
57.
7 and 28
58.
9 and 45
59.
9 and 8
60.
8 and 7
61.
20 and 5
62.
36 and 4
63.
7 and 12
64.
5 and 6
In Exercises 65-78, find the LCM by using prime factorization.
65.
54 and 12
66.
24 and 36
67.
20 and 35
68.
18 and 54
69.
12 and 18
70.
40 and 32
71.
42 and 54
72.
56 and 28
73.
36 and 16
74.
27 and 72
75.
72 and 48
76.
24 and 30
77.
25 and 49
78.
36 and 25
In Exercises 79-88, use any method to find the LCM.
79.
n and n 2
80.
x and x 4
81.
x and 2x
82.
3n and n
83.
9m and 6m
84.
4a and 12a
85.
4 and a 3
86.
m 2 and 3
87.
5 and n
88.
x and 6
3
2015 Carreon
Math 40
Prealgebra
Section 4.4 – HOMEWORK
In Exercises 89-116, perform the indicated operation.
89.
5 2

6 3
90.
7 1

8 4
91.
5 1

6 3
92.
2 1

3 9
93.
2 1

9 6
94.
5 1

6 4
95.
1 3

5 4
96.
3 5

5 8
97.
4  6
 
5  10 
98.
4  9 
 
5  10 
99.
1 1
 
2 8
1 1
100.  
2 3
101.
3 7

10 15
102.
7 5
103.  
8 32
105.
1  3
 
12  16 
107. 
109.
3  3
 
10  4 
11  5 
 
14  21 
1  2
111.     
4  3
11 5

24 16
104. 
106.
3  17 
 
10  40 
108. 
110.
4 6

35 7
5  3
 
12  8 
5  3
 
12  8 
7  1
112.     
8  2
113.
9 5
 
8 32
114.

4 9

15 10
115.
5  7 
 
24  36 
116.
5  7
 
12  18 
4
2015 Carreon
Math 40
Prealgebra
Section 4.4 – HOMEWORK
In Exercises 117-136, perform the indicated operation.
117.
4x 2

7 3
118.
1 3x

2 5
119.
u u

2 6
120.
u u

10 5
121.
4 3

9 n
122.
3 2

4 n
a a
123.  
2 5
124. 
3a 7a

4 12
125.
9 7

c 8
126.
2 3

c 7
127.
3 2

x 3x
128.
5 4

4x x
129. 
7 1

2u u
130. 
5 1

6u u
131.
1 1

n n2
132.
1 1

n2 n
133.
8
8
 2
2c 6c
134.
12 12

5c 2 10c
135. 
3
5

10a 15a 2
136. 
5
9

6a 15a 2
5
2015 Carreon
Math 40
Prealgebra
Section 4.4 – HOMEWORK
In Exercises 137-142, solve the following application problems.
137. How much stronger is a
1
1
-horsepower garage door opener compared to a -horsepower garage door
2
3
opener?
138. What is the total weight of
1
1
1
-ton of sand, -ton of gravel, and -ton of cement? If your truck can only
2
3
5
safely carry 1-ton load, can it be used to deliver the items mentioned above in one trip to a job site?
139. A group of foresters planted
night, a fire destroyed
7
11
acre of seedlings on Friday and
acre of seedlings on Saturday. That
12
12
3
acre of seedlings. How many acres of seedlings remained?
4
140. How much fencing will be needed to enclose a rectangular wildflower preserve that is
1
mile long and
3
1
mile wide?
6
141. How much fencing will be needed to enclose a rectangular city park that is
1
mile long and
12
3
mile wide?
8
142. Marguerite needs
also needs
1
1
cup of milk to make mashed potatoes and cup of milk to make veggie dip. She
2
8
3
cup of milk to make pudding for dessert. How much milk does she need in all?
4
6
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