Gmap warp on a custom map script

[SSS]

Having another problem, since Im not good with math.

Here it is, can anyone help?
Im trying to show where the player is on the custom map..
the custom map position is on the screen at
x(screenwidth / 2 - 210)
y(screenheight / 2 - 210)
the map image is shown there, the map image is 420x420
I cant figure the math out same map size as I used for the warping up there....
but it needs to show up using something like this.
showimg 201,@@@Me,this.x+playerx/420,this.y+playery/420;
changeimgvis 201,4;

any math experts out there that can help?