Question

The sum of digit of a two digit number is 12. the number obtained by inter changing the digit exceeds the given number by 18 .find the number

Answer 1

Let the tens digit be x and the units digit be y.
So the number=10x+y
A.q.
x+y=12
x=12-y (equation 1)
After interchanging the number we get
=10y+x
Also,
(10y+x)-(10x+y)=18
10y+x-10x-y=18
9y-9x=18
9(y-x)=18
y-x=18/9
y-x=2
From eauation 1 x=12-y
So,
y-(12-y)=2
y-12+y=2
2y=12+2
2y=14
y=14/2
y=7
And x=12-y
=12-7
=5
Hence the number is 57.