Question

a sum of 625 is made up of 80 notes which are either of 10 rupees or 5 rupees.The number of 5 rupees notes is.​

Answer 1

let no  of ten rupee notes be x

and that of 5 rupee be y

x+y=80

x=80-y

also

5y+10x=625

5y+10(80-y)=625

5y+800-10y=625

175=5y

y=35

therefore 35 notes of 5 rupees