The problem above uses the concept of ratio and proportion. The ratio between the cost and amount of the organic milk should always be equal. The proportion between two cases is shown below, ($2.52 / 0.5 gallon) = (x / 4 gallons) Solving for x gives x = 20.16. Therefore, 4 gallons of organic milk costs $20.16.
I believe the pressure inside the tires decreases in the winter because of the cold and increases in the summer when the air is heated up making it expand and add more pressure
