Question

a bag has a total of 120 notes in denominations of rs 2, rs. 5 and rs. 10. the total value of the notes in the bag is rs 760. if there were twice as many notes rs. 5 , the total value of the notes will be 960. find the number of rs 10 notes in the bag?

Answer 1

So there are three variables, rs2 label x, rs5 label y, rs10 label z
Lets write equeations using these variables.
x+y+z=120 (A bag has a total of 120 notes)
2x+5y+10z=760 (total value)
2x+5*2y+10z=960 (twice as many rs5)

3 variables, 3 independent equations will give solution. There are a fair few ways to solve this.