At the gas station each liter of gas costs $3 but there is a promotion that for every beverage you purchase you save 0.20 cents on gas. Is your total savings on gas proportional to the number of beverages you purchase?

When a relationship between two variables is proportional, it means that there is a constant ratio between the two variables. In this case, the answer is yes, there is a proportional relationship between total savings on gas and the number of beverages purchased.

You save $0.20 on gas for every beverage you buy.

Let s=dollars saved on gas, and b=# of beverages purchased

s=.2b

or

s=b/5