SOLUTION: Tom's home is 1800m from his school. One morning he walked part of the way and then ran the rest. If it took him 20 min or less to get to school and he walks 70m/min and runs 210m/

Question 332850: Tom's home is 1800m from his school. One morning he walked part of the way and then ran the rest. If it took him 20 min or less to get to school and he walks 70m/min and runs 210m/min how far did he run?
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
Tom's home is 1800m from his school.
One morning he walked part of the way and then ran the rest.
If it took him 20 min or less to get to school and he walks 70m/min and runs
210m/min how far did he run?
:
let x = distance he ran
then
(1800-x) = distance he walked
:
Write a time equation: time = dist/speed
:
Run time + walk time = 20 min
+ = 20
Multiply by 210 to get rid of the denominators, results
x + 3(1800 - x) = 210 * 20
:
x + 5400 - 3x = 4200
x - 3x = 4200 - 5400
-2x = -1200
x =
x = +600 meters he ran
:
:
Confirm our solution by finding the times
1800 - 600 = 1200 m he walked
walk time: 1200/70 = 17.14 min
run time: 600/210 = 2.86 min
-----------------------------
total travel time: 20 min

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