A man buys certain number of books for Rs.720.If a cost per book was Rs.5 less,the number of books that could be bought would be 2 more.What is the cost per book?

• Let 'x' be the cost of 1 book then (720/x) is the no of books
  New case : cost per book is 5 less so (x-5) and the no o f books now will be
  720/(x-5) which is 2 more than previous so final eq.
  (720/x) + 2 = 720/(x-5)
  sol. (x=45)
• 12 years agoHelpfull: Yes(2) No(0)
• Cost of one Book is 6rupees .
  n -no.of books
  x -cost for each book.
  nx=720(It is given)
  n(x-5)=n+2
  nx=6n+2 so n=(nx-2)/6
  n=718/6=120(119.66 approximately) The no.of books is always integers
  x=720/120 =>6
  so the cost for each book is 6 rupees.
  
• 12 years agoHelpfull: Yes(0) No(1)
• Let the No. of books purchased be x
  then, the cost per book=720/x
  as new cost of book is 5 less, thus the cost per book=(720/x)-5
  Now, No. of books purchased is 2 more at the same price, the equation would become
  (x+2)*(720-5x)/x
  simplifying, the quadratic equation follow as under;
  x^2+2x-288=0
  solving, we get the values of x=-18 or 16
  Thus the no. of books purchased would be 16
  and the cost per book=720/16=Rs.45
• 12 years agoHelpfull: Yes(0) No(0)