coords.cs

public static GeoCoordinate AddMetersToGeoCoordinate(GeoCoordinate current, double metersH, double metersV)
{
    return new GeoCoordinate(current.Latitude + (metersH / (111111)), current.Longitude + (metersV / (111111 * Math.Cos(current.Latitude))));
}

meters.cs

public static double MetersToPixels(double meters, double latitude, double zoomLevel)
{
    var pixels = meters / (156543.04 * Math.Cos(latitude) / (Math.Pow(2, zoomLevel)));
    return Math.Abs(pixels);
}

public static double PixelsToMeters(double pixels, double latitude, double zoomLevel)
{
    return pixels  * (156543.04 * Math.Cos(latitude) / (Math.Pow(2, zoomLevel)));            
}