On Thursday 15*3=<<15*3=45>>45 books were sold.

On Friday 45/5=<<45/5=9>>9 books were sold

Adding up all three days 15+45+9=<<15+45+9=69>>69 books were sold by Friday

# Answer

69
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
A new book sold 15 copies at the bookstore on Wednesday. On Thursday the book sold three times that many copies. On Friday the book sold one-fifth the number of copies it did on Thursday. How many copies of the book did the bookstore sell by Friday?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
69
A new book sold 15 copies at the bookstore on Wednesday. On Thursday the book sold three times that many copies. On Friday the book sold one-fifth the number of copies it did on Thursday. How many copies of the book did the bookstore sell by Friday?
train