Does anyone know the answer to this all ready tried and it was wrong?

Which is the graph of the piecewise function f(x)? f(x)=[tex]f(x) = \left \{ {{-x+1, x\leq 0 } \atop {x+1, x\ \textgreater \ 0}} \right.[/tex]

Me n o w. i need t h i s. 10 points

Find the distance between (7,-6) and (-3,-9)