9514 1404 393
Answer:
5 miles
Step-by-step explanation:
Time/speed/distance problems can be worked a number of ways. Here, we want to know the distance walked. We know the total time and the total distance and the two different speeds. So, we can use a variable to represent the value we want to know: w = distance walked (in miles).
The total time is 9:00 -6:50 = 2:10 = 2 1/6 hours = 13/6 hours.
The total time is the sum of times for the two parts of the trip: walking and riding.
walking time = walking distance/walking speed
= w/3
riding time = riding distance/riding speed
= (20-w)/30
The total time is that given above:
w/3 +(20-w)/30 = 13/6
10w +(20 -w) = 65 . . . . . . . . multiply by 30
9w = 45 . . . . . . . . . . . . subtract 20, collect terms
w = 5 . . . . . . . . . . . divide by 9
The girl walked 5 miles.
