Heena has only ₹2 and ₹5 coins in her purse. If in all she has 80 coins in her purse amounting to ₹232,find the number of ₹5 coins

Question

Please find out using linear equation

 

Answer 1

Assume that the ₹2 coins are X1 and ₹5 coins are X2, the matrix becomes:

 

X1 +    X2 = 80

2X1 + 5X2 = 232

 

or [1  1]

    [2  5]  = [A]

 

 and the output matrix [B] is

 

   [80]

   [232}

 

remember that the solution can be found by inverting the matrix [A]

which yields 

[1.666   -.3333]

[-.6666  .33333]

 

multiplying [A] inverse times [B] yields the result

 

[56]

[24]

 

Therefore number of ₹5 coins is 24

 

Hope this helps