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
- Letx¼the speed of the boat as indicated on its speedometer
Rate Time ¼ Distance
Upstream x 32
1
2
2
1
2
(x3)
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
- Letx¼the airspeed of the plane
Rate Time ¼ Distance
To Waltersville x 25 5 5(x25)
To Mt. Pleasant xþ 20 4 4(xþ20)
144 LESSON 13 Solving Distance Problems