SQL topshirig‘i 7.6 darajasi

Quyidagi jadval berilgan:

students
id name grade
1 John 91
2 Alex 92
3 Evans 72
4 Alisa 85
5 Donella 66
6 Lauren 79
7 Matthew 56
8 Andrew 62
9 Richard 55
10 Sam 50

Uning uchun quyidagi masalalarni yeching:

Задание 1

O‘rtacha balldan yuqori ball olgan talabalarning o‘rtacha ballini toping.

Задание 2

90 balldan yuqori bahosi bo‘lmagan talabalarning sonini toping.