Among the given elements: - Eu (Europium), Er (Erbium), Tb (Terbium), Yb (Ytterbium), and Lu (Lutetium) all belong to the lanthanoid series. Cm (Curium) belongs to the actinide series.
Hence, the number of elements that do not belong to lanthanoids is 1 (Cm).
The portion of the line \( 4x + 5y = 20 \) in the first quadrant is trisected by the lines \( L_1 \) and \( L_2 \) passing through the origin. The tangent of an angle between the lines \( L_1 \) and \( L_2 \) is: