Question

A sum of Rs 500 is in the form of denomination of Rs 5 and Rs10. If the total number of notes is 90, find the number of notes of each type.

Answer 1

Let us assume that the number of Rs.5 notes are x and number of Rs.10 notes are y.
We know that total number of notes are 90.
so we can say
x + y = 90............ (1)
So, the number of Rs.5 notes in the sum will be Rs.(5 * x) and the number of Rs.10 notes in the sum will be Rs.(10 * y).
With this, we can form an equation
5x + 10y = 500.....................(2)
since the total notes in the sum will amount to Rs.500
Dividing equation (2) on both sides by 5, we get
x + 2y = 100...............(3)
Now, Subtract the corresponding LHS and RHS of Equation (1) from equation (3)
(x + 2y) - (x + y) = 100 - 90
therefore, we get y = 10
putting that in equation (1), we get x = 80