Question

a man has certain notes of denominations of 20 and 5 which amount to 160 if the number of notes of each kind are interchanged they amount to 60 More than before find the number of notes each kind

Answer 1

Let's assume no of 20notes as X

5 notes as y

20x+5y=120

20y+5x=120+60=180

By solving

4x+y=24...........i

X+4y=36

By multiplying i by -4

-16x-4y=-96

+(X+4y=36)

By adding we get

-15x=-60

X=4

By substituting X in i

Y=8