Question 1121009
Hello.
Given their working time: 3 hrs, 4 hrs, 5 hrs.

It's apparent that the ratio between the working speeds of Mr.Adam, Mr.Barney and Mr.Joe is 5:3:2. Therefore we can interpret their working speeds as 5k, 3k, 2k, in books carried per hour. (k is a constant).


Then by the total number of books given,
{{{5k*3+3k*4+2k*5=999}}}. solve for k: k=27.(nice integer!)

Adam's books: 27*5*3=405 books.