The independent variable belongs on the x-axis (horizontal line) of the graph and the dependent variable belongs on the y-axis (vertical line).
x-axis represents days/year/time (major interval set to 7); y-axis represents tasks.
For example, if you are following the number of cancer cases per year, you plot the number of cancer cases on the y-axis because that number is different for each year, and the value you plot depends on which year you choose (you are choosing the year, so year goes on the x-axis; you are reporting the number of cancer
For this question you would divide $8.52 by 36 pencils to get about $0.24 per pencil for brand A rounded to the nearest cent. Then divide $9.98 by 48 pencils to get about $0.21 per pencil for brand B rounded to the nearest cent.
