Give the step-by-step reasoning process and then the final answer. Kurt's old refrigerator cost $0.85 a day in electricity. He recently bought a new energy-efficient refrigerator that only cost $0.45 a day in electricity. How much money does Kurt save in a 30-day month with his new refrigerator?
The old refrigerator costs $0.85 a day so for 30 days it costs .85 * 30 = $25.50. The new refrigerator costs $0.45 a day so for 30 days it costs .45 * 30 = $13.50. Over 30 days, Kurt saves 25.50 - 13.50 = $12.00 a month with his new refrigerator.
The final answer: 12.