Answer:
45
Step-by-step explanation:
Let the unit place be ‘x'
Tenth place be y
The number is 10y+x
x+y = 9 (according to the condition) (1)
Digits are interchanged Unit place' y ‘& tenth place ‘ x'
New no is 10x +y
This is 9 more than the original number
10x+ y = 10y+x +9
10x-x+y-10y = 9
9x-9y= 9
x-y = 1 (dividing by 9) (2)
Adding the two equations
2x = 10
x= 5
Substituting the value of x in first equation
y = 4
The number is 45, the original number is 54 this is 9 more of the new number.
