Question 1147091: A boy walked for 3 hours and cycled For 4 hours covering a distance of 80km.
A week later he walked for 2 hours and cycled for 5 hours covering 100km.
What were his average speed for walking and cycling, if his walking and cycling speed were constant
Answer by ankor@dixie-net.com(22740)   (Show Source):
You can put this solution on YOUR website! A boy walked for 3 hours and cycled For 4 hours covering a distance of 80km.
A week later he walked for 2 hours and cycled for 5 hours covering 100km.
What were his average speed for walking and cycling, if his walking and cycling speed were constant
:
let w = his walking speed
let s = his cycling speed
:
Write a dist equation for each trip; dist = time * speed
:
walk dist + cycle dist = total dist
3w + 4s = 80
2w + 5s = 100
use elimination, multiply the 1st eq by 2 and the 2nd eq by 3
6w + 8s = 160
6w + 15s = 300
--------------- subtraction eliminates w, find
0 - 7s = -140
s = -140/-7
s = +20 mph is his cycling speed
:
Find w using the 2nd equation
2w + 5(20) = 100
2w = 100 - 100
w = 0 mph is the walking speed???
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