Question

The sum of two digits of s number is 15 if 9 is added to the munber digits are reveresed

Answer 1

let the number be xy

then we may write:

10x+y=15

10x+y+9=10y+x ⇒ -9x+9y=9 ⇒ -x+y=1

x=14/11

y=25/11

hence number =10*14/11+25/11=15 ans.