Math Word Problems Demystified - A Self Teaching Guide

7. Letx¼the time it will take Walter to complete the project.

45

75

þ

45

x

¼1 LCD¼ 75 x

751 x

45

751

þ 75 x

45

x

¼ 75 x 1

45 xþ 3375 ¼ 75 x

45 x
 45 xþ 3375 ¼ 75 x
 45 x

3375 ¼ 30 x

3375

30

¼

301 x

301

112 :5 minutes¼x

8. Letx¼the time it takes to fill the tank if all three pipes are open.

1

60

xþ

1

80

xþ

1

90

x¼1 LCD¼ 720

72012

1



x

601

þ

7209

1



x

801

þ

7208

1



x

901

¼ 720  1

12 xþ 9 xþ 8 x¼ 720

29 x¼ 720

291 x

291

¼

720

29

x¼ 24 :83 minutes

192 LESSON 17 Solving Work Problems