# Solving systems word problem

• October 22nd 2009, 03:25 PM
t-dot
Solving systems word problem
I'm having issues getting the equations for this problem.

The longest cable suspension bridge in the world is Akashi Kaikyo Bridge in Japan. It has one long span and two short spans. Each short span is half the length of the long span. The total length of the bridge is 3560m. What is the length of each span?

This is what I'm having issues with:
I do not know if i should be representing the short span and long span by x and y values or if they should both be the same variable.

if i use two variables i know that:
x +y = 3560
and then x + y/2 should be part of the other equation.
i think.

ahh
help.
• October 22nd 2009, 03:57 PM
skeeter
Quote:

Originally Posted by t-dot
I'm having issues getting the equations for this problem.

The longest cable suspension bridge in the world is Akashi Kaikyo Bridge in Japan. It has one long span and two short spans. Each short span is half the length of the long span. The total length of the bridge is 3560m. What is the length of each span?

This is what I'm having issues with:
I do not know if i should be representing the short span and long span by x and y values or if they should both be the same variable.

if i use two variables i know that:
x +y = 3560
and then x + y/2 should be part of the other equation.
i think.

ahh
help.

define variables ...

let $x$ = length of the long span

$y$ = length of a short span

The total length of the bridge is 3560m

$x+2y = 3560$

Each short span is half the length of the long span.

$y = \frac{x}{2}$

solve the system
• October 22nd 2009, 04:03 PM
t-dot
oh man thanks.
these word problems are getting to me.
big help
:)