Question

a number consists of two digits whose sum is 5 when the digits are reversed the number becomes greater than 9 find the number

Answer 1

Let the number be 10x +y  , 
    x = ten's place  , y = one's place

x + y = 5          ---> [1]

reversed no: ,
10y + x

10x+ y + 9 = 10y+x
9x - 9y = -9

x - y = -1            ---> [2]

Adding equations 1 and 2

x + y = 5
x - y = -1
======
2x = 4

x = 2

x -y = -1

2 - y = -1

2 + 1 = y

3 = y

the number is :-

10x + y 

10 x 2 + 3
  = 23

The no: is 23

Answer 2

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