Question 314635
4.at the beginning of a walk, bill and nancy are 8.8 miles apart. 
if they leave at the same time and walk in the same direction, bill overtakes nancy in 11 hours.
 if they walk towards each other they meet in 1 hour. what are their speeds?:
:
let b = Bill's walking speed
let n = Nancy's walking speed
:
walking the same direction they're effective speed is the difference
walking towards each other they're effective speed is the sum
:
"Same direction" equation
Write a time equation: Time = dist/speed
{{{8.8/((b-n))}}} = 11
8.8 = 11(b-n)
8.8 = 11b - 11n
Simplify, divide by 11
.8 = b - n
Or
b - n = .8
:
"Toward equation"
{{{8.8/((b+n))}}} = 1
8.8 = 1(b + n)
b + n = 8.8
:
Use elimination
b - n = .8
b + n = 8.8
---------------addition eliminates n, find b
2b = 9.6
b = 4.8 mph is Bill's walking speed
:
Find n
4.8 + n = 8.8
n = 8.8 - 4.8
n = 4 mph is Nancy's walking speed