Use the image to answer the question.
An illustration shows two graphs depicting cost of gasoline per gallon in dollars in store A and B.
The first graph shows cost of gasoline per gallon in dollars in store A. The horizontal axis shows gallons ranging from 0 to 20 in increments of 5. The vertical axis shows the cost in dollars ranging from 0 to 70 in increments of 10. Four data points are plotted on the graph at left parenthesis 0 comma 0 right parenthesis, left parenthesis 5 comma 20 right parenthesis, left parenthesis 10 comma 40 right parenthesis, and left parenthesis 15 comma 60 right parenthesis. A line connects all the data points.
The second graph shows cost of gasoline per gallon in dollars in store B. The horizontal axis shows gallons ranging from 0 to 10 in increments of 2. The vertical axis shows the cost in dollars ranging from 0 to 30 in increments of 2. Three data points are plotted on the graph at left parenthesis 0 comma 0 right parenthesis, left parenthesis 4 comma 14 right parenthesis, and left parenthesis 8 comma 28 right parenthesis. A line connects all the data points.
The proportional relationship between the cost of gasoline and the number of gallons of gasoline from Store A and Store B are displayed in the graphs. Use the graphs to interpret the store that has the cheaper cost of gasoline per gallon.
Based on the graphs, it can be observed that for Store A, the cost of gasoline per gallon increases at a constant rate of $4 for every 5 gallons. However, for Store B, the cost of gasoline per gallon increases at a constant rate of $7 for every 4 gallons.
Comparing the two stores, it is evident that Store A has a cheaper cost of gasoline per gallon because the rate at which the cost increases for Store B is higher than Store A. Therefore, Store A offers a more cost-effective option for purchasing gasoline per gallon.