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

### Instruction:
Tell me the totla number of goal difference for goals against of 30 and played less than 18

### Inputs:
table_name: table, columns: ['Team', 'Played', 'Draw', 'Lost', 'Goals For', 'Goals Against', 'Goal Difference', 'Points']

### Response:
SELECT COUNT Goal Difference FROM table WHERE Goals Against = 30 AND Played < 18