To find the final temperature of a monatomic ideal gas from a P vs V graph, one must utilize the ideal gas law, which relates pressure (P), volume (V), and temperature (T). The initial temperature at point A can be used alongside the changes in pressure and volume to calculate the final temperature. The area under the curve or the specific path taken on the graph may also provide insights into the work done on or by the gas, impacting its thermal state. Understanding the relationships between these variables is crucial for accurate calculations. Ultimately, applying the ideal gas law allows for determining the final temperature based on the provided graph data.