Question

the sum of the digits of a two digit number is 9. when you interchange the places of the number then it is equal to 9 less than the original number. what is the original number?

Answer 1

hello here is your answer by Sujeet yaduvanshi ☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝☝

Let to be 10' digit number be x
Let to be 1 unit digit be y

then,


x+y=9

Again,,
10x+y=10y+x-9
10x-x+y-10y=-9
9x-9y=-9

x-y=-9/9
x-y=-1


then,

Solving the equation 1 and 2

x+y=9
x-y=-1

______
2y=10
y=10/2
y=5

again,,
x+y=9
x+5=9
x=9-5
x=4



then,


Required original Number=10x+y

10*4+5
40+5
45



:)


by Incredible Sujeet




that's all