Question

The sum of the digits of a two-digit number is 3.if we subtract 9 from the number,the Digits are interchanged.find the original number.

Answer 1

Le the two digits be x and y.

x+y = 3 …(1)

10x+y-9 = 10y+x, or

9x=9y=9, or

x-y=1 …(2)

Add (1) and (2)

2x=4 or x = 2,ad so y = 1

So the number is 21.

Check: 21–9 = 12. Correct.

Answer 2

Heya!!!

Any two digit number ( ab ) can be written like this

10a + b

Example.

34

10 ( 3 ) + 4

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Let the digit be xy

ACCORDING TO THE QUESTION

x + y = 3 ... equation ( i )

=>

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

=>

9x -9y = 9

=>

x - y = 1 .... equation ( ii )

Adding Both the equations we get

2x = 4

x = 2 And y = 1

So, The two digit number is 21

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VERIFICATION

2 + 1 = 3 ✓✓✓✓

21 - 9 = 12

12 = 12 ✓✓✓✓✓