Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
Which rebound was 8 and has and ast that was less than 57?

### Inputs:
table_name: table, columns: ['Nationality', 'No [a ]', 'Pos [a ]', 'From', 'School/club', 'Pts [b ]', 'Reb [b ]', 'Ast [b ]']

### Response:
SELECT AVG Reb [b ] FROM table WHERE No [a ] = 8 AND Ast [b ] < 57