Give the step-by-step reasoning process and then the final answer. Gunther needs to clean his apartment. It takes him 45 minutes to vacuum the carpets, 60 minutes to dust the furniture, 30 minutes to mop the floors in his kitchen, and 5 minutes to brush each cat, and he has three cats. If he has 3 hours of free time available, and he uses this time to clean his apartment, how many minutes of free time will he have left after he cleans the apartment?
It will take 3 * 5 = 15 minutes to brush his cats. All together, it will take 45 + 60 + 30 + 15 = 150 minutes to clean his apartment. In three hours, there are 60 * 3 = 180 minutes. Thus, he will have 180 - 150 = 30 minutes of free time remaining.
The final answer: 30.