Answer
domain: [0,8]
range: [0, 9600]
Work Step by Step
Only 8 bags are available. Any number between 0 and 8 can be used.
The range is affected by how many bags can be used. Since 0 bags can be used, 0 square feet would be covered. Since 8 bags can be used $8*1200 = 9600$ square feet can be covered.