Question

A sum of 500 is in the form of denominations of RS 5 AND Rs 10.if the total no.of notes is 90 find the no of notes of each denomination.
hint let the no.of 5 rupees notes be x ,then no.of 10 rupees notes=90-x

Answer 1

80 notes of rs 5 and 10 notes of rupees 10

acc to ques
5x+10(90-x)=500
5x+900-10x=500
10x-5x=900-500
5x=400
x=400/5=80
and (90-x)=(90-80)=10

Answer 2

Let no. of Rs 5 notes be x and no. of Rs 10 notes be y
Total number of notes is 90 ⇒ x + y = 90 ........(1)
Total amount = 500
5x + 10y = 500   ...(2)
Multiply equation (1) by 10
10x + 10y = 900  .....(3)
Subtract eqution (2) from equation (3)
10x + 10y = 900
5x + 10y = 500
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5x = 400
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x = 80
y = 10

No. of Rs 5 notes = 80
No. of Rs 10 notes = 10