static void Main(string[] args)
{
int[] a = new int[10];
int[] b = new int[10];
int oblPl = 0, oblU = 0;
for (int i = 1; i < 10; i++)
{
Console.WriteLine("Ukazhite ploshad' " + i);
a[i] = int.Parse(Console.ReadLine());
Console.WriteLine("Ukazhite urozhai " + i);
b[i] = int.Parse(Console.ReadLine());
oblU = oblU + a[i] * b[i];
oblPl = oblPl + a[i];
}
Console.WriteLine("Oblastnaya ploshad' " + oblPl);
Console.WriteLine("Oblastnaya urozhainost' " + oblU/oblPl);
Console.ReadLine();
Случайно не это?