To answer this first we will subtract d amount of dollars Boy had by d amount of dollars he had left in d end. den we will divide d amount of dollars he used by d amount of books he bought. den d answer will be d amount of money each book cost. Lets do it:-
The rounded answer would be $41.33 for each book if they cost the same. The unrounded answer would be $41.33333..... and goes on. You find the answer by subtracting the leftover money from the original amount of money, which is, $266-$18. And that equals $248. Then you divide, $248÷6, which would equally divide the amount of money between the 6 books to find the price for each. $248÷6=$41.33. I hope this helped :)
