Question 987119
Hi there 
12 edges to a cube.
Each edge measures 2x - 8/72x + 24
2x - 8/72x + 24 * 12
2x - 8/6x + 2
2(x - 4)/2(3x - 1)
Cancel top and bottom 2's
Total Length = x - 4/3x - 1
Hope this helps :-)