Question

I have a total of rupees 300 in coins of denomination ₹1,₹2 and₹5. The number of ₹2 coin is 3 times the number of ₹5 coin. The total number of coins is 160. How many coins of each domination are with me

Answer 1

Let the no. of Rs. 5 coins be x

no of Rs. 2 will be  3x

Rs. 1 coin be.  160-3x-x = 160-4x

the amount I have,

from Rs. 2 coins= 3x= 3x2 = 6x

from Rs. 5 coins= x= 5x

from Rs. 1 coin = (160-4x)x1 = 160-4x

Total money Rs.300

6x+5x+160-4x = 300

7x + 160 = 300

7x = 140

x = 20

No. of Rs. 2 Coins = 3x20= 60

No. of Rs. 5 coins = x=20

No. of Re. 1 coin = 160-4x20 =80

And That's The answer !! I learned this concept in class 4th!

Answer 2

let the no. of rs 5 coins be x

& the no. of rs 1 coin be y

& no. of rs 2 coins be 3 x

a.q.t total no. of coins = 160

x + 3x+y = 160

4x + y = 160 eq. 1

again a.q.t total rs = 300

5x + 2(3x) + 1y = 300

11x + y = 300 eq. 2

by elimination method

on subtracting both the equations

4x + y = 160

-11x -y = -300

=-7x =-140

  x =20

on putting the the value of x in eq 2

4(20) + y =160

80 + y = 160

y =80

now,

no of rs 2 coins = 3(20)

                      = 60

no. of rs 5 coins = 20

no. of rs 1 coins=80