Question

a man has certain notes of denomination₹20 and ₹5 which amount to ₹380.If the number of notes if each kind is interchanged ,they amount to ₹60 less as before.Find the number if nites of each denomination.

Answer 1

let the denomination of note 20 be x and that of 5 rupee be y
.20x + 5y = 380.
again when denomination is interchanged
we have
5x + 20y = 380-60
5x + 20y = 320
after solving the equation we get
x= 16 and y=12

Answer 2

Answer: 20x + 5y = 380 equation 1

5x + 20y = 380 - 60 5x + 20y = 320equation 2 Equation -1 is multiply by 4. 80x + 20y = 1560. 5x + 20y = 320. When we subtract sign is always change. So. 80x + 20y = 1560. 5x - 20y = -320. ______________________________75x =. 1240. X = 1240/75. X=16. From equation 1 we have find value of y. 20*16+5y = 380. 5y = 380 - 320. 5y = 60. Y=12