Question 736505
 a Kayaker traveled 20km/h into the current and 7/5 the speed with the current,
 What is the speed of the kayaker in still water and
 what is the speed of the current?
:
Find 7/5 of the speed of 20 km/h
{{{7/5}}}*20 = 28 km/hr
:
let s = speed in still water
let c = the rate of the current
then write an equation for each way
s + c = 28
s - c = 20
------------Addition eliminates c, find s
2s = 48
s = 48/2
s = 24 km/h in still water
:
I'll let you find the current. 
:
:
A motorcycle breaks down and the rider must walk the rest of the way to work.
 the motorcycle averaged 55mph, and the rider walks at the speed of 5mph.
 The distance from home to work is 100 miles, and the total time for the trip was 4 hours.
 how far did the motorcycle rider walk?
:
let w = distance walked
the total distance is 100 mi, therefore:
(100-w) = distance rode
:
Write a time equation time = dist/speed
ride time + walk time = 4 hrs
{{{((100-w))/55}}} + {{{w/5}}} = 4
Multiply by 55 to clear the denominators, resulting in:
100 - w + 11w = 55(4) 10w = 220 - 100
10w = 120
w = 120/10
w = 12 miles he walked!
:
:
You can check this by finding the actual times he walked and rode
12/5 = 
88/55 =
---------
total time ___