Question

the sum of the digit in a two digit number is 7 if we add 9 to the number the digits are interchanged find the number
please with full explain .......

Answer 1

HIII!

Maybe this could be the answer.

HOPE IT HELPS!!

Answer 2

Hey there !!

Let the ten's digit of the original number be x .

And, the unit's digit of the original number be y.

Now, A/Q

⇒ x + y = 7.............(1) .

The original number = 10x + y .

Number obtained on reversing the digits = 10y + x .

Now,  

⇒ 10y + x = 10x + y + 9 .

⇒ 10x - x  + y - 10y = -9.

⇒ 9x - 9y = -9.

⇒ 9( x - y ) = -9.

⇒ x -y = -9/9 .

⇒ x - y = -1...........(2) .

On substracting equation (1) and (2), we get

x + y = 7.

x - y = -1.  

-   +     +

_________

⇒ 2y = 8.

⇒ y = 8/2.

∴ y = 4 .

On putting the value of y in equation (1), we get  

⇒ x + y = 7.

⇒ x + 4 = 7.

⇒ x = 7 - 4 .

∴ x = 3 .

∵ Original number = 10x + y .

= 10 × 3 + 4 .

= 30 + 4 .

= 34 .

Hence, the original number is 35 .

THANKS

#BeBrainly.