Question

A car and a truck left Washington, DC traveling in opposite directions. The car traveled 19 miles per hour faster than the truck, and at the end of 8 hours they were 1448 miles apart. What was the average speed of each vehicle?

Answer 1

The truck traveled at

81 mph and the car traveled at

100 mph.

Answer 2

Let
x = truck speed
x + 19 = carriage speed
by definition we have that distance is equal to the speed by time.
Therefore, we have then
1448 = (x + (x + 19)) * (8)
Rewriting the equation, we have then:
1448 = (2x + 19) * (8)
1448 = 16x + 152
Clearing x
x = (1448-152) / (16) = 81 mi / h
x = 81 mi / h (truck speed)
The speed of the car is:
x + 19 = 81 + 19 = 100 mi / h
answer:
The car's speed is 100 mi / hr
The truck's speed is 81 mi / hr