Mr. Powell is a famous motivational speaker. He travels across the country by jet and gives an average of seven presentations a week. He gives his speeches in auditoriums that are always full and hold an average of 1500 people each. He charges $20 per person at each of these speeches. His average expenses for each presentation, including renting the auditorium, are about $16,000. The cost of meals, motels, jet travel, and support personnel total $80,000 per week. How many weeks will Mr. Powell need to travel if he wants to earn $180,000 per year?