Question

the sum of the digit of a two digit number is 9.if 9 is added to the number the digits interchange their places find the number

Answer 1

Hey!!!!!

________

Let the unit digit be x and ten's digit be y.

Then

ATQ,

=> x + y = 9-----(1)

and

=> 10x + y + 9 = 10y + x

=> 9x - 9y = -9

=> x - y = -1-------(2)

Adding (1) and (2)

=> x + y + x - y = 9 - 1

=> 2x = 8

=> x = 4

Using in (1)

=> y = 5

Original number = 40 + 5 = 45

Thus the number is 45.

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Hope this helps ✌️

Answer 2

★ Ello ★

here is your answer !!

let the tens digit be x

and unit digit be y

according to question !

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


hence , the number is

10x + y

now , digits interchanged.

10y + x

according to question !

10x + y + 9 = 10 y + x


=> 9 ( x - y ) = -9


x - y = -1. ------------------------(2)


from equation 1 and 2 we get

x + y = 9
x - y = -1
========

2x = 8

x = 4


on putting the value of in equation 1 we get y= 5




hence ,

the number is


10 x + y

=> 10 × 4 + 5


=> 45


★ ans= 45 ★


hope it helps you dear !!



$thanks$