Dịch đoạn hội thoại sau: How much does one banana cost?

dịch  
How much does one banana cost ?
Lan : can i help you , hoa ?
Hoa : yes , please. i'm trying to do this math question.
Lan : which one ?
Hoa : number three 
Lan : that is a difficilt question 
Hoa : i know my answer isn't right 
Lan : let"s look at the exercise 
Hoa : mu answer is three bananas cost 18,000 dong
         i know that is not the price of bananas 
Lan : i see your problem .there are only two zeros in the cortect answer .you have three . erase one zero 
Hoa : oh! i see . thanks ,lan 
Lan : my pleasure