5- 1 = 4, the money that Xiaoming spent on four ballpoint pens and 1 pen is equal to the money that Xiaohua spent on 1 pen and three ballpoint pens.

4- 1 = 3

44 ÷ 2 = 22 yuan

22× 3 = 66 yuan

3× 4 = 12. In this way, if Xiao Ming buys 12 ballpoint pens and 3 pens, it will cost 66 yuan.

﹙66-22﹚÷﹙ 12- 1﹚

=44÷ 1 1

= 4 yuan. A ballpoint pen, 4 yuan.

﹙22-4﹚÷3

= 18÷3

6 yuan, a pen, 6 yuan.