A shopkeeper buys some books for Rs. 80. If he had bought 4 more books for the same amount, each book would have cost Rs. 1 less. Find the number of books he bought.
Total cost of books = Rs.80
Let the number of books = x
So the cost of each book = Rs
Cost of each book if he buy 4 more books = Rs
As per given in equations:
Since number of books cannot be negative,
so the number of books he brought is 16.
Let the frist number be x then the second number be 9 - x as the sum of both number is 9.
Now the sum of their reciprocal is , therefor
If x = 6 then other number is 3.
And, if x = 3 then other number is 6.
Hence numbers are 3 and 6.