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.