Question

The sum of the digits of a two digit number is 7 and if 9 is added to the digits the digits are reversed. Find the number.

Answer 1

Let first digit be x and second digit be y .

Let original no be = 10 x X + Y

A/Q

1.   X + Y = 7

X= 7-Y

2.  10 x X + Y + 9 = 10 x Y + X

10X + Y + 9 = 10Y + X

10X - X + 9 = 10Y - Y

9X + 9 = 9Y

9X - 9Y = -9

X - Y = -1

7-Y-Y = -1

-2Y = -1- -7

-2Y = -8

Y = 4

X = 7-4

  = 3

Original no = 34

Answer 2

HERE IS UR ANSWER………………

LET TWO DIGIT NUMBER IS 10X+Y.
AS GIVEN,
X+Y= 7

10X+Y+9= 10Y+X
9 = 10Y+X-(10X+Y)
9X-9Y = 9
9(X-Y) = 9
X-Y= 1

BY USING ELIMINATION METHOD,

X+Y=7
X-Y=1
- + -
_______
2Y= 6
Y= 3
X+3 = 7
X= 4.
SO, THE NUMBER IS
10X+Y= 43.