SOLUTION: A truck enters a highway driving at 60 mph. A car enters the highway at the same place 11 minutes later and drives 72 mph in the same direction. From the time the car enters the hi

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: A truck enters a highway driving at 60 mph. A car enters the highway at the same place 11 minutes later and drives 72 mph in the same direction. From the time the car enters the hi      Log On


   

Question 834032: A truck enters a highway driving at 60 mph. A car enters the highway at the same place 11 minutes later and drives 72 mph in the same direction. From the time the car enters the highway, how long will it take the car to pass the truck?
Answer by josgarithmetic(39618) About Me  (Show Source):
You can put this solution on YOUR website!
The truck has been traveling on the highway for 11 minutes and the car travels on this highway for t minutes; when the two reach the same position, the truck had traveled for t+11 minutes.

____________speed____________time(hours)_______________distance
truck_______60_______________t+11/60__________________d
car_________72_______________t________________________d

That LOOKS like two variables as unknown, but you also will make TWO equations using these variables.

60%28t%2B11%2F60%29=d and 72t=d and d is the same value in both equations.
60%28t%2B11%2F60%29=72t
60t%2B11=72t
11=12t
highlight%28t=11%2F12%29 miles; not quite a full mile.