Analysis process:

Dong lent (Dong-18) yuan,

Lend Dongdong (money-108) yuan,

Encyclopedia price = English-Chinese dictionary price X 3,

D+(Dong-18)= encyclopedia price = D+Dong-18

Dong+(Ding Dingqian-108)= English-Chinese dictionary price = Dong+Ding Dingqian-108

Encyclopedia price-English-Chinese dictionary price = (D+D-18)- (D+D-108)

= 108- 18=90 yuan = English-Chinese dictionary price X 2, so English-Chinese dictionary price =45 yuan.

Encyclopedia price = English-Chinese dictionary price X 3=45 X 3= 135 yuan.

Finally, 108- 18=90 yuan, 90÷2=45 yuan, 45×3= 135 yuan.