Question

help..........................

Answer 1

let unit digit be x amd tens digit be y
Number = 10y + x
x+y =9......(1)
9 (10y + x) = 2( 10x + y)
90y + 9x = 20x + 2y
88y = 11x
11x - 88y = 0
11( x - 8y ) = 0
x - 8y = 0.........(2)
solve 1 &2
-9y = 9
y = 1
and
x = 8
now,
number = 10y + x
10* 1 + 8
18