Solution: The first method and the second method are to see 6 pencils as pens and 0.5 pencils as 3 pencils respectively. The third method and the fourth method are to do equations, and set the pen and pencil to X yuan respectively! The following is the answer process:

Method 1: Because a pen is equivalent to six pencils, it can be seen that it is 3+6=9 (pencils): 10.8÷9= 1.2 (yuan), so this pen is 1.2x6=7.2 (yuan). The following is the specific solution process:

3+6=9 (yuan); Pencil: 10.8÷9= 1.2 (yuan); Pen: 1.2x6=7.2 (Yuan)

A: Pencil 1.2 yuan, pen and 7.2 yuan.

Similarly, method 2:

3÷6=0.5 ;

Pen: 10.8(0.5+ 1)= 7.2 yuan;

Pencil: 7.2÷6= 1.2 (Yuan)

A: Omit.

Method 3: Pencil X yuan, pen 6x yuan, depending on the meaning:

3x+6x = 10.8；

9x = 10.8；

X= 1.2, then this pen is 6x=7.2 (yuan).

A: Omit.

Method 4: Set the pen as X yuan and the pencil as x÷6. According to the meaning of the question:

3*(x÷6)+x= 10.8

0.5x+x = 10.8

1.5x = 10.8

X= 7.2, and the pencil is 7.2÷6= 1.2 (yuan).

A: Omit.