A sum of Rs. 800 is in the form of denominations of Rs. 10 and Rs. 20.If the total number of notes be 50, find the number of notes of each type.

**.** Let there be *x* notes of Rs 10.

Total number of notes = 50.

∴ Number of notes of Rs 20 = (50 – *x*)

Total sum of money = Rs 800

∴ 10*x* + 20 (50 – *x*) = 800

⇒ 10*x* + 1000 – 20*x* = 800

⇒– 10*x* = 800 – 1000

⇒ – 10*x* = – 200

⇒ *x* = 20

∴ 50 – *x* = 50 – 20

= 30

So, there are 20 notes of Rs 10 and 30 notes of Rs 20.

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