The old refrigerator costs $0.85 a day so for 30 days it costs .85*30 = $<<0.85*30=25.50>>25.50
The new refrigerator costs $0.45 a day so for 30 days it costs .45*30 =$<<0.45*30=13.50>>13.50
Over 30 days, Kurt saves 25.50-13.50 = $<<25.50-13.50=12.00>>12.00 a month with his new refrigerator
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