Select whether the relationship between each pair of quantities is proportional.
1. A small pizza costs $9.00 and each additional topping costs $0.75. (Yes/No)
2. A health club charges $45 per month. (Yes/No)
3. A bike rental store charges $20 as a flat fee, plus $5 per hour. (Yes/No)
4. A bathtub holding 40 gallons of water drains at a rate of 6 gallons per minute. (Yes/No)
5. A car travels 60 miles in 1 hour, 120 miles in 2 hours, and 180 miles in 3 hours. (Yes/No)
6. A student earns $12 for each hour she tutors. (Yes/No)
