SOLUTION: I have to be at a certain place at a certain time and find that I shall be 20 minutes too late if I walk at 3km/hr 10 minutes too early if I walk at 4km/hr. How far I have to walk?

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Question 962620: I have to be at a certain place at a certain time and find that I shall be 20 minutes too late if I walk at 3km/hr 10 minutes too early if I walk at 4km/hr. How far I have to walk?
Found 2 solutions by ankor@dixie-net.com, MathTherapy:
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
I have to be at a certain place at a certain time and find that
I shall be 20 minutes too late if I walk at 3km/hr
10 minutes too early if I walk at 4km/hr.
How far I have to walk?
:
The walking time difference between the two trips; 20 min + 10 min = 30 min
30 min = 1%2F2 hr
:
let d = the distance he has to walk
:
Write a time equation; time = dist/speed
d%2F3 - d%2F4 = 1%2F2
multiply the equation by 12, cancel the denominators and you have
4d - 3d = 6
d = 6 km is the distance he walked

Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!

I have to be at a certain place at a certain time and find that I shall be 20 minutes too late if I walk at 3km/hr 10 minutes too early if I walk at 4km/hr. How far I have to walk?
Let distance be D
Then time that it’d take to get to destination 20 minutes late = D%2F3
Time that it’d take to get to destination 10 minutes early = D%2F4
Therefore, D%2F3+-+20%2F60+=+D%2F4+%2B+10%2F60 ------> D%2F3+-+1%2F3+=+D%2F4+%2B+1%2F6
4D – 4 = 3D + 2 ------ Multiplying by LCD, 12
4D – 3D = 2 + 4
D, or distance = highlight_green%286%29 km