We are given a graph of pounds of grapes vs dollar spent.
To know what $1 worth of grapes is, we go to the horizontal axis to locate 1 and trace up to where it meets up with the graph and on getting that point on the graph, we trace it left to the vertical axis to get $0.5 (50 cent)
To get the dollars' worth for each grape, we locate one on the vertical axis and trace it right to where it cuts the graph. This can easily be seen to