SOLUTION: tom quig travelled 270 miles east of st louis . for most of the trip he travelled 70mph , byt for one period of thme he was slowed to 20 mph due to major accident . if the total ti

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: tom quig travelled 270 miles east of st louis . for most of the trip he travelled 70mph , byt for one period of thme he was slowed to 20 mph due to major accident . if the total ti      Log On


   

Question 109709: tom quig travelled 270 miles east of st louis . for most of the trip he travelled 70mph , byt for one period of thme he was slowed to 20 mph due to major accident . if the total time of travel was 6 hours , how many miles did he drive on the reduced speed?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
tom traveled 270 miles. For most of the trip he traveled 70 mph, but for one period of time he was slowed to 20 mph. if the total time of travel was 6 hours, how many miles did he drive at reduced speed?
:
Let x = no. of miles at 20 mph
Then
(270-x) = no. of miles at 70 mph
:
Write a time equation: Time = Distance/speed
:
20 mph time + 70 mph time = 6
x%2F20 + %28%28270-x%29%29%2F70 = 6
:
multiply equation by 140, get rid of the denominators:
140*x%2F20 + 140*%28%28270-x%29%29%2F70 = 140*6
:
Cancel out the denominators and you have:
7x + 2(270-x) = 840
:
7x - 2x + 540 = 840
:
5x = 840 - 540
:
5x = 300
:
x = 300%2F5
x = 60 miles at 20 mph
;
:
Check solution by finding the distances:
60/20 + 210/70 =
3 + 3 = 6