Question

2 The sum
of the 2 digits number is 9. also nine times this number obtained by reversing the3 order of the digits. find the number. ​

Answer 1

Answer:

The sum of digits f a two digit number is 9. Also nine times this number is twice the number obtained by reversing the order of digit. Hence, the number is 10y + x = 10 × 1 + 8 = 18. 

Answer 2

Correct Question :

The sum of digits of a two digit number is 9. Also, nine times this number is twice the number obtained by reversing the order of digit. Find the number.

Solution :

Let the unit digit and tens digits of the number be ' x ' and ' y ', respectively.                

• Given Number = 10y + x

                 

After reversing the digits of the number :

• 10x + y    

Now,

According to the question,                  

 x + y = 9 ______________ (i)                 

⇒  9 (10y + x) = 2(10x + y)                  

⇒  88y - 11x = 0                  

⇒ -x + 8y =0 _______ ( ii )       

Now, Add equation ( i ) and ( ii ). We get,

•   9y = 9                  

∴ y = 1 _________ (iii)                  

     Substitute the value of ' y ' in equation ( i ). We get,

x + 1 = 9

⇒ x = 9 - 1

∴ x = 8

Finally,

The number = 10y + x

= 10 ( 1 ) + 8

= 10 + 8

= 18

Therefore,

18 is the required number.

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