Question

the number of a two digit number is 12. if the digits are reversed ,the new number is 12 less than double the orignal . find the number

Answer 1

Let the no.= 10x+1y;
= Digits= x and y;
a/q 
x+y=12;......................i
y+x-12=2(x+y)
=y+x-12=2x+2y
we know x+y=12
y+x-12=2(12)
y+x-12=24
y+x-36=0.....................ii
On solving two eqaution
x+y=12
x+y=36
and solve yoy get 

Answer 2

let the one'2 place digit be x 
then the ten's place digit is 12-x
the no. will be 10(12-x)+x
                    =120-9x
on reversing the digits
the no. will be 10x+12-x
                   =9x+12
according to the question
2(120-9x)-12=9x+12
                  x=8
ones place digit =8
tens place digit=4
therefore the number is 48