Math Word Problems Demystified - A Self Teaching Guide

5 ðx
 25 Þ¼ 4 ðxþ 20 Þ

5 x
 125 ¼ 4 xþ 80

5 x
 4 x
 125 ¼ 4 x
 4 xþ 80

x
 125 ¼ 80

x
 125 þ 125 ¼ 80 þ 125

x¼205 miles per hour

4. Letx¼the speed of the current
   Rate  Time ¼ Distance
   Downstream 18
   x 1.75 1.75(18
   x)

Upstream 18 þx 1.25 1.25(18þx)

1 : 25 ð 18 þxÞ¼ 1 : 75 ð 18 
xÞ

22 : 5 þ 1 : 25 x¼ 31 : 5 
 1 : 75 x

22 : 5 þ 1 : 25 xþ 1 : 75 x¼ 31 : 5 
 1 : 75 xþ 1 : 75 x

22 : 5 þ 3 x¼ 31 : 5

22 : 5 
 22 : 5 þ 3 x¼ 31 : 5 
 22 : 5

3 x¼ 9

31 x

31

¼

9

3

x¼3 miles per hour

5. Letx¼the airspeed of the plane
   Rate  Time ¼ Distance
   To East Grove x
   22 6 6(x
   22)

To Uniontown xþ 22 4 4(xþ22)

LESSON 13 Solving Distance Problems 145