Please help me with (b).

This exercise is from Mathematics of Investment and Credit (5th edition)

*2.3.23 Show that the following relationships are valid, and illustrate them using line diagrams: (a) (la)n +(Da)n = (n+1). an n (b) (la)n = 3x6-1 and (IS) Ski k=1 k=0 (IS) - - n (Is)n + n (d) (D)n = (Da)n + n-am (e) (Dan an *2.3.23 Show that the following relationships are valid, and illustrate them using line diagrams: (a) (la)n +(Da)n = (n+1). an n (b) (la)n = 3x6-1 and (IS) Ski k=1 k=0 (IS) - - n (Is)n + n (d) (D)n = (Da)n + n-am (e) (Dan an