Question

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

Answer 1

Answer:

Here's your answer

Let the summer be x and y

NUMBER IS 10x+y

ACCORDING TO QUESTION

x+y= 9

By reversing

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

90x+9y= 20y+2x

90x-2x= 20y-9y

88x= 11y

$\frac{88x}{11} = y \\ \\ 8x = y$

So For x

x+y= 9

$x + 8x = 9 \\ \\ 9x = 9 \\ \\ x = 1$

and For y

x+y= 9

1+y= 9

y= 8

The number is 18 or 81

Hope it helps ✌....

Answer 2

Hey mate

Answer :

Let unit = X

Tens digit = y

Number will 10 times the tens digit unit the unit digit .

Hence number will 10 y + X

Sum of digits are 9

So that

X+ y = 9 ______( 1 ).

Nine times this number is twice the number obtained by reversing the order of the digits .

9 ( 10 y + X ) = 2 ( 10 X + y )

90 y + 9x = 20x + 2y

88y - 11x = 0

Divide by 11 we get .

8y-x = 0 ______(2)

X+y=9 ________(1)

Adding both equation we get

9y=9

y=9/9=1

Plug this value in equation first we get :

X+y=9

X+1=9

X=8

So our original number is 10y + X=10×1+8=18

Thanks .