A simple example of eliminating single variables on the rhs.

Original grammar:

S -> A
S -> AB
S -> aSb
A -> a
A -> C
A -> aA
C -> CBa
C -> ba
B -> b

Replacement grammar:

S -> a
S -> CBa
S -> ba
S -> aA
S -> AB
S -> aSb
A -> a
A -> CBa
A -> ba
A -> aA
C -> CBa
B -> b

A simple example of eliminating rhs's with more than 2 symbols:

Original grammar:

S -> ASB
S -> ab
A -> a
B -> b
B -> bSSa

Replacement grammar:

S -> DB
D -> SB
S -> ab
A -> a
B -> b
B -> Ea
E -> FS
F -> bS