Question

There are 90 coins comprising of 5 and 10 paise coins. the value of all coins is rs 7 how many 5 paisa coins are there?

Answer 1

Total no: of coins = 90
Let no: of 5 paisa coins be 'a' 
Let no: of 10 paisa coins be 'b'
Given,
5*a + 10*b = 7 Rs = 700 paisa
a + b = 90....(i)
5*a + 10*b = 700...(ii)
(i)*10== 10*a + 10*b = 900...(iii)
(iii) - (ii)
5*a = 200
a = 40
b = 50
Number of 5 paisa coins = 40
Hope it helps.

Answer 2

Answer:

Step-by-step explanation:

Total no: of coins = 90

Let no: of 5 paisa coins be x

Let no: of 10 paisa coins be y

Given,

5*x + 10*y = 7 = 700

ax+ y= 90....(i)

5*x + 10*y= 700...(ii)

(i)*10== 10*x + 10*y = 900...(iii)

(iii) - (ii)

5*x = 200

X= 40

Y= 50

Number of 5 paisa coins = 40

Hope it helps