Question

I have 20 rupees. i bought 1, 2, 5 rupee stamps. they are different in numbers by the reason of no change, the shop keeper gives 3 one rupee stamps. so how many stamp(s) i have.

Answer 1

let the stamps be 3 + 2x + 5y = 20
2x + 5y = 17
so no one can be zero
hence there are two solution
either x = 1 , y = 3
or x = 6 and y=1