What will richards english score most likely be if he's spend 7 hours a week studying english?

It is usually a bad idea to extrapolate beyond the available data, unless the underlying model can be considered reliable. IMO, there is no reason to believe additional study will yield additional return, since the points tend to flatten out around a score of 40.

Here it appears the line has a slope that shows score increasing by 15 points for every 2 hours of study time. Hence, adding 2 hours to the final point on the graph (from 5 to 7) might be expected to add 15 points to the 48 points shown on the graph.

If the model is correct, Richard's score can be expected to be 63 if he studies 7 hours.