SOLUTION: A truck heads north at a constant speed of 80 km/h. A car leaves 20 minutes later heading north along the same road and travelling at a constant speed of 90 km/h. Write an

Question 759942: A truck heads north at a constant speed of 80 km/h. A car leaves 20 minutes
later heading north along the same road and travelling at a constant speed of
90 km/h.

Write an equation that could be used to determine how much time in
hours, t, the car travels until it catches up to the truck.
**The correct answer is 90t = 80(t+1/3) , but I need help understanding why**
Found 2 solutions by josgarithmetic, MathTherapy:
Answer by josgarithmetic(39616) (Show Source): You can put this solution on YOUR website!
The truck travels for 1/3 hour plus some unknown time, t.
Twenty minutes is 1/3 hour.
This distance is kilometers.

The car, starting from the same departure point, travels for time, t, and catches-up with the truck.
This distance is kilometers.
Answer by MathTherapy(10551) (Show Source): You can put this solution on YOUR website!

A truck heads north at a constant speed of 80 km/h. A car leaves 20 minutes
later heading north along the same road and travelling at a constant speed of
90 km/h.

Write an equation that could be used to determine how much time in
hours, t, the car travels until it catches up to the truck.
**The correct answer is 90t = 80(t+1/3) , but I need help understanding why**

Let time it takes car to catch up to truck (get to meeting point) be T

Then time it'll take truck to get to meeting point = T + 1/3, since the truck will take a longer time to get to the meeting point as it's traveling at a slower speed

Distance car travels to get to meeting point = 90(T), or 90T

Distance truck travels to get to meeting point = 80(T + 1/3)

Both vehicles would've traveled the same distance, so:
RELATED QUESTIONS
A truck heads north at a constant speed of 22m/s. A car leaves 20 minutes later heading... (answered by josgarithmetic)
a car is driving north on a straight two line road at a constant speed of 80 km/h, a... (answered by josmiceli,ikleyn)
Car A passes point O heading east at a constant rate of 20 mi/h; car B passes the same... (answered by Fombitz)
A car leaves Hartford traveling north at 56 km/h. Another car leaves Hartford one hour... (answered by josmiceli)
A plane is heading north-west at 480km/h and is in contact with another plane which... (answered by ankor@dixie-net.com)
A train leaves a station at 11am, heading north. Another train, 320 km away, leaves at... (answered by josmiceli)
Car A passes point O heading east at a constant rate of 40 mi/h; car B passes the same... (answered by stanbon)
Two speedboats head off from the same point on a lake at the same time. One heads north... (answered by josgarithmetic)
a car leaves LA traveling north at 59 km/ph. another car leaves LA an hour later on the... (answered by stanbon)