ok, i think i figured it out but i'm not sure how let me try to break it down again
so if Fgravity is -9.8 then the Fnormal is 9.8?
so is Ffriction = u * Fnormal?
which is 1.176 is a?
and then i used
vf - vi / 2a
which gave me 140.689
did i get it or was this a lucky guess?