Question

19. The sum of the digits of a two digit number is 9. Also 9 times this number is twice the
number obtained by reversing the order of the digits. The number is
(A) 63
(B) 18
(C) 36
(D) 81​

Answer 1

Answer:

Step-by-step explanation:

Given :-

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.

To Find :-

The Number

Solution :-

Let the unit digit and tens digits of the number be x and y                  

Number = 10y + x                  

Number after reversing the digits = 10x + y    

            

According to the question,                  

⇒  x + y = 9 ... (i)                  

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

⇒  88y - 11x = 0                  

⇒ -x + 8y =0 ... (ii)                  

Adding equation (i) and (ii), we get                  

⇒  9y = 9                  

⇒  y = 1 ... (iii)                  

Putting the value in equation (i), we get                  

⇒  x = 8                  

Hence, the number is 10y + x = 10 × 1 + 8 = 18.

answer is [b]=18

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