Question

A hundred rupee note was changed to ten rupee notes and twenty rupee notes, eight notes in all. How many tens and how many twenties?

Answer 1

Total amount of money = Rs.100

Total number of ten and twenty rupee notes = 8

Let the total number of ten rupee notes be x.

The total number of twenty rupee notes = 8 − x

Total amount made by ten rupee notes = x × Rs.10 = Rs.10x

Total amount made by twenty rupee notes = (8 − x) × Rs.20

= Rs.20(8 − x)

= Rs (160 − 20x)

∴ 10x + 160 − 20x = 100

⇒ −10x = 100 − 160

⇒ −10x = −60

⇒ x =

⇒ x = 6

8 − x = 8 − 6 = 2

Thus, the total number of ten and twenty rupee notes is 6 and 2 respectively.