Question

the sum of the digits of a 2 digits number is 9 . the number is 6 times the unit digit. find the number

Answer 1

let digits of two digit no be x and y
then
X+y=9

also given
10x+y=6y
10x=5y
y=2x
putting in 1st equation
3x=9
x=3
y=6
hence the number is 36