Finding average speed of a moving shadow, please help, this is urgent!?

Question

A light, on top of a post is 14 feet above the ground. At night a 5 foot woman is standing 18 feet from the post. Her shadow is 10 feet long and her 6 foot friend is 16 feet away from the post.

http://i38.tinypic.com/2emlb14.jpg

Starting 18 feet from the post, the woman walks directly away from the post for 4 seconds at a rate of 3 feet per second. Find the average speed (total distance divided by total time) of the tip of her shadow during that 4 second interval

Answer 1

let shadow's tip total distance be d.

x / 5 = (18 + 3*4 + x) / 14

x / 5 = (x + 30) / 14

14x = 5x + 150

9x = 150

x = 150 / 9 = 50 / 3

d = (x + 30) - (10 + 18)

= 50/3 + 2

= 56/3

average speed

= d / (4 seconds)

= 56 / 3*4

= 14 / 3

= 4.667 feet per second

Answer 2

I answered this exact question yesterday, here's the answer I gave pandapandapandapandapandapanda!!!.  It's gunsuptech's answer, not fenderbender22000's answer.  fenderbender's answer is inaccurate.

http://answers.yahoo.com/question/index;...