Question

A two digit number is such that the sum of its digit is 9 on adding 9 to the number the digit are reversed find the number​

Answer 1

Answer:

let it be xy

x + y = 9

xy + 9 = yx

let x = 4

let y = 5

Answer would be 45. If you add 9 to it, you get 54, in which digits of 45 are reversed.

Answer 2

Answer:

let the number be 10x + y

where x is the tenth digit and y is once digit.

we took it 10x + y because remember the expanded form of a two digit number.

ATP-1

x+y=9

x=9-y........ (1)

ATP-2

10x+y+9=10y+x

putting value of x form eq 1

10(9-y)+y+9=10y+9-y

90-10y+y+9=10y+9-y

99-9y=9y+9

dividing both side by 9

11-y=y+1

2y=10

y=5

now putting the value in eq 1

x=9-5

x=4

therefore the number is

10(4)+5

40+5

45

hope it helps....