Question

Two cars leave Denver at the same time and travel in opposite directions. One car travels 10 mi/h faster than the other car. The cars are 660 mi apart in 6 h. How fast is each car traveling?

40 mi/h and 50 mi/h
60 mi/h and 40 mi/h
60 mi/h and 70 mi/h
50 mi/h and 60 mi/h

Answer 1

50 mph and 60 mph

Explanation:

Represent the two speeds by s and f (slower and faster). Then f = s + 10.

We find the distance traveled by each car separately, sum up the absolute values of these distances and set this sum equal to 660:

(s + s + 10)(6 hr) = 660 mi. Simplifying this, we get:

2s + 10 = 110, or

2s = 100.

Then s = 50 mph and f = (50 + 10) mph, or 50 and 60 mph (matches the last possible answer)

Answer 2

D.) 50 mi/h and 60 mi/h

Explanation: