Math Word Problems Demystified - A Self Teaching Guide

3 ðxþ 25 Þ¼ 4 ðx
 25 Þ

3 xþ 75 ¼ 4 x
 100

3 x
 4 xþ 75 ¼ 4 x
 4 x
 100


xþ 75 ¼
 100


xþ 75 
 75 ¼
 100 
 75


x¼
 175


x


 1

¼

175

1

x¼175 miles per hour

2. Letx¼the speed of the boat as indicated on its speedometer

Rate  Time ¼ Distance

Upstream x
 32

1

2

2

1

2

(x
3)

Downstream xþ322(xþ3)

2

1

2

ðx
 3 Þ¼ 2 ðxþ 3 Þ

5

2

ðx
 3 Þ¼ 2 ðxþ 3 Þ

21

1



5

21

ðx
 3 Þ¼ 2  2 ðxþ 3 Þ

5 ðx
 3 Þ¼ 4 ðxþ 3 Þ

5 x
 15 ¼ 4 xþ 12

5 x
 4 x
 15 ¼ 4 x
 4 xþ 12

x
 15 ¼ 12

x
 15 þ 15 ¼ 12 þ 15

x¼27 miles per hour

3. Letx¼the airspeed of the plane

Rate  Time ¼ Distance

To Waltersville x
 25 5 5(x
25)

To Mt. Pleasant xþ 20 4 4(xþ20)

144 LESSON 13 Solving Distance Problems