Select each situation that can represent a proportional relationship.


The price of buying x gallons of gas at $3 a gallon.


The total amount of money a child earns from doing chores when she earns $10 a week for w weeks.


The total amount of weight a kitten gains in w weeks when it gains 4 ounces per week and started at a weight of 6 ounces.


The price of renting a scooter for m miles when it costs $0.75 per mile plus a base fee of $2.50.