Question

Sum of a two digit number is 7 . When we interchange the digits , it is found that the resulting new number is greater than the original number by 9 . What are the two digits?

Answer 1

Let the digit be 10x+y

where x+y=7...(1)

when digits are interchanged.

it become 10y+x

Given: 10y+x-(10x+y)=9

10y+x-10x-y=9

9y-9x=9

y-x=1... (2)

Solving (1) and (2) simultaneously y=4 and x=3

so number=10x+y

10 (3)+4

30+4=34.

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.Hope is helps you

Answer 2

Step-by-step explanation:

let the unit place be x and the tense place be y

Orignal no. -> 10y + x

Reversing no. -> 10x + y

According to the question:

x + y =  7 ........(1)

=    10x + y   =   10y + x +9

=    9x = 9y +9

=    9x - 9y + 9

= x - y = 1  ..............(2)

From (1), x = 7-y   ...........(3)

substituting  (3) in (2),

=  7 - y - y = 1

=  7-1 = 2y

=   2y = 6

=  y = 3

we know that x+y = 7

x + 3 = 7

Ans : x = 4 and y = 3