SOLUTION: gary drove to Sarnia. Part of the trip was along major highways and the rest was along country roads. the speed linit is 100km/h on the hgihgways and 80km/h on the other roads. he

Question 158729: gary drove to Sarnia. Part of the trip was along major highways and the rest was along country roads. the speed linit is 100km/h on the hgihgways and 80km/h on the other roads. he spent a total of 12 hours driving 1050 km. write a system of equations that would allow you to find how much time did he spend on each type of road.
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
Part of the trip was along major highways and the rest was along country roads.
The speed limit is 100km/h on the highways and 80km/h on the other roads.
He spent a total of 12 hours driving 1050 km. Write a system of equations
that would allow you to find how much time did he spend on each type of road.
:
Let x = time on highway
Let y = time on country roads
:
The time equation:
x + y = 12
y = (12-x); use for substitution
:
The dist equation; dist = speed * time:
100x + 80y = 1050
;
Substitute (12-x) for y in the above equation; find x
100x + 80(12-x) = 1050
100x + 960 - 80x = 1050
100x - 80x = 1050 - 960
20x = 90
x =
x = 4.5 hrs at 100 km/hr
and
y = 12 - 4.5 = 7.5 hrs at 80 km/hr
;
:
Check solutions by finding the total dist:
100(4.5) + 80(7.5) =
450 + 600 = 1050;
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