Question

Stefanie's train will leave the station in 24 minutes and she is y miles from the station. To catch the train, she walks at a speed of 4 miles per hour and later runs at a speed of 8 mph. Write an equation in terms of y for the distance she has to walk, w, to reach the station in 24 minutes. My question is...why is the answer w=16-5y/5 or w=3.2-y. I don't know how to figure it out

Answer 1

Since the total distance is y, if she walks a distance w, then she runs the rest of the way (y-w).

since time = distance/speed, and her total time is 2/5 hours,

w/4 + (y-w)/8 = 2/5
2w + y-w = 16/5
w+y = 16/5
w = 16/5 - y
w = (16-5y)/5

Answer 2

Wait... where did yo get the 2/5