This is the code that work
double xPostion = (124 - Math.abs(aVertex.getLongitude()));
xPostion = xPostion / 57;
xPostion = xPostion * this.myWidth;
double yPostion = 49 - aVertex.getLatitude();
yPostion = yPostion / 25;
yPostion = yPostion * this.myHeight ;
57 is difference in longitude from eastern most continental US and western most.
25 is the difference in latitude from the norther most continental US and the southern most
124 is the longitude of the western most continental US.
49 is the latitude of the norther most continental US.