Which of the following angles cannot be constructed using ruler and compass only ?

Below angles can be drawn using following

120° = 90° + 30° or 60° + 60° (where 30° is the bisected angle of 60° )

135°= 90° + 45°

37.5° is the bisected angle of 75° and 75° can be drawn using 90° and 60°.

But 40° cannot be drawn.