Based on the description of the graph, if Amanda's earnings increase linearly with the number of hours she works, you can estimate her earnings for seven hours by interpreting the plotted line.
Since I can't see the actual graph but need to provide a possible prediction, if we assume that the earnings are consistently rising and the values cluster around the options you provided, the most reasonable predictions based on typical rates might be $75, $105, or $110 for seven hours of work.
If Amanda makes around $10-15 per hour on average, then a prediction of $75 (assuming she earns $10.71 per hour) or $105 (assuming she earns $15 per hour) could work, but without the actual graph, I would suggest either $105 or $110 seems like a solid estimate for seven hours based on common rates.
If I had to choose one based on potential increases for a more extended time, I would lean toward $105 as a common earning for that duration, but reviewing your graph will yield the most accurate number.