If you help I will give you brainliest

9514 1404 393

  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.