Math Word Problems Demystified - A Self Teaching Guide

9. Letx¼the time it takes Mary to make the costume and 2x¼the time
   it takes Sam to make the costume.
   6
   x

þ

6

2 x

¼1 LCD¼ 2 x

2 x

6

x

þ 2 x

6

2 x

¼ 2 x 1

12 þ 6 ¼ 2 x

18 ¼ 2 x

18

2

¼

21 x

21

9 hours¼x

10. Letx¼the time it takes both people to seed the field.
    1
    8

þ

1

8

xþ

1

6

x¼1 LCD¼ 24

243

1



1

81

þ

243

1



x

81

þ

244

1



x

61

¼ 24  1

3 þ 3 xþ 4 x¼ 24

3 þ 7 x¼ 24

3 
 3 þ 7 x¼ 24 
 3

7 x¼ 21

x¼3 hours

Since the man has already worked an hour before his daughter

started, it will take 1þ 3 ¼4 hours to complete the job.

LESSON 17 Solving Work Problems 193