 # ML Aggarwal Solutions Class 9 Mathematics Solutions for Problems on Simultaneous Linear Equations Exercise 6 in Chapter 6 - Problems on Simultaneous Linear Equations

Question 17 Problems on Simultaneous Linear Equations Exercise 6

A man has certain notes of denominations Rs. 20 and Rs. 5 which amount to Rs. 380. If the

a number of notes of each kind is interchanged, they amount to Rs. 60 less as before. Find the

a number of notes of each denomination.

Let’s consider the number of 20 rupee notes to be x

And the number of 5 rupee notes be y

Then, according to the given conditions we have

20x + 5y = 380 … (i) and

5x + 20y = 380 – 60

⇒ 5x + 20 y = 320 … (ii)

Now, multiplying (i) by 4 and subtracting with (ii) we get

80x + 20y = 1520

5x + 20 y = 320

(-)--(-)----(-)-------

75x = 1200

x = 1200/75

x = 16

On substituting the value of x in (i), we get

20(16) + 5y = 380

320 + 5y = 380

5y = 380 – 320 = 60

y = 60/5

y = 12

Therefore, the number of 20 rupee notes = 16 and the number of 5 rupee notes = 12

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