From the graph, which liquid should have higher boiling point? How do you know?
Boliling point / composition diagrams
The relationship between boiling point and vapour pressure
If a liquid has a high vapour pressure at a particular temperature, it means that its molecules are escaping easily from the surface.
If, at the same temperature, a second liquid has a low vapour pressure, it means that its molecules aren't escaping so easily.
What does that imply about the boiling points of the two liquids? Don't read on until you have tried to think this out!
There are two ways of looking at this. Choose whichever seems easiest to you. It doesn't matter how you work this out - it is the result that is important.