How to write expression in such case - 13 ( path to sacle expression)

Hi,

I want to animate the path of the Cell according to the null's position. Is there any way I can do that?

I dnt wanna do it manually for losing the synchronicity or rythm. I wanna match the path movement animation extactly according to the null animation. when The null is away the cell should be a bit bigger in scale and when the null is  compressed the path should be small. I tried connecting path's scale property  with null's scale. the result is psychotic. Please help me. Please.