i refer so many results and modified my code its working
foreach (var rate in rateing)
{
sum += Convert.ToInt32(rate.Rate);
}
if(rateing.Count()!= 0)
{
float avg = (float)sum / (float)rateing.Count();
saloonusers.Rate = avg;
}
else
{
saloonusers.Rate = (float)0.0;
}