The graph shows the relationship between the total cost and the number of erasers bought at the student store. which statement is true? each eraser costs $1.00. each eraser costs $1.50. three erasers cost $6. seven erasers cost $3.50.

Each eraser will cost u 50 cents

so 7 erasers will cost (7 * 0.50) = 3.50 <==

The correct option is D.
The only true statement is the one written at option D, all other options are wrong.
From the graph, you can see that one eraser cost 50 cent and two erasers cost one dollar. If you trace the graph, you will notice that on the vertical axis where $3.5 is written, the dot there tallies with figure 7 on the horizontal axis. That is telling you that 7 erasers cost $3.5.