[Ashish Gupta]

I think This should solve your problem..

Use this for point A :

x= value[0] - thisComp.layer("Null 2").effect("Slider Control")("Slider");
y = value[1];
[x,y]

And this for point B :

x= value[0] + thisComp.layer("Null 2").effect("Slider Control")("Slider");
y = value[1];
[x,y]

[Ashish Gupta]

I think this is what u r looking for .. .

https://blog.motionboutique.com/text-bounds-expresssion-364

[Ashish Gupta]

You can easily do this by using a keyword value in the expression.

temp = thisComp.layer("Null 1").effect("Slider Control")("Slider");
[temp, value[1]]

or

u can also assign a static number to y value

x = thisComp.layer("Null 1").effect("Slider Control")("Slider");
y=40;
[x,y];