I have a little problem with a little maths question thats bugging me. We have a test on monday for this stuff so I don't have chance to ask my teacher before the test.

Four computer terminals (A,B,C,D) are located along a wall. A server is located at some point x along the wall andseperate cables go to each computer.

Heres a diagram:

(a) Explain why the total length of cable needed isCode:A B C D -------------------------------------------------------- wall... -6 -2 0 3 5

|x+6| + |x+2| + |x-3| + |x-5|.

(b) Where should the server S be located to minimize the total length of the cable.

I know for (b) I can just draw it on a calculator and find the minimum, but I don't get how in (a) its |x-3| and |x-5|, I would have expected it to be |x+3| because its the length...

Any explanations would be really appreciated.