c# console problem

Hello Guyz, need your help

The output should be like this;

Enter Student Name:     ahmet taha
Enter Math Grade:       90
Enter Science Grade:    86
Enter English Grade :   95

Total Average : 90
Passed

The highest Score is : 95

The lowest Score is : 86

here is my code:

double avg;
Console.Write("Enter Student Name:\t");
string name = Console.ReadLine();
Console.Write("Enter Math Grade:\t");
int math = Convert.ToInt32(Console.ReadLine());
Console.Write("Enter Science Grade:\t");
int science = Convert.ToInt32(Console.ReadLine());
Console.Write("Enter English Grade :\t");
int english = Convert.ToInt32(Console.ReadLine());
avg = (math + science + english) / 3;
Console.Write("\nTotal Average : {0}", avg);
if( avg >= 75)
{
    Console.Write("\nPassed");
}
else
{
    Console.Write("\n");
    Console.Write("Failed");

}

int[] arr1 = new int[math];
int[] arr2 = new int[science];
int[] arr3 = new int[english];
// int[] arr1 = new int[[math] || [science] || [english]];
//int[] arr1 = new int[science];
int[] arr1 = new int[english];
int mx, mn;
mx = arr1[0];
mn = arr1[0];
for (int x = 1; x < arr1.Length; x++)
{
    //if (arr1[x] > mx || arr2[x] > mx || arr3[x] > mx)
    if (arr1[x] > mx)
    {
        mx = arr1[x];
        //mx = arr2[x];
        //mx = arr3[x];
    }
    //if (arr1[x] < mn || arr2[x] < mn || arr3[x] < mn)
    if (arr1[x] < mn)
    {
        mn = arr1[x];
        //mn = arr2[x];
        //mn = arr3[x];
    }
}
Console.Write("\nThe Highest Grade is : {0} ", mx);
Console.Write("\nThe Lowest Grade is : {0} ", mn);