Question

The sum of the digits of a 2 digits
number is 9. If the digits are
reserved, the new number is
9 less than 3 times the original number
find TheOriginal number.​

Answer 1

Answer:

27 is original number.

Step-by-step explanation:

sum of digits of 2-digit no.=9

let first digit= x

now second digit=9-x

no.=10(x)+9-x = 9x+9

by reversing digits:

first digit =9-x

second digit=x

no.=10(9-x)+x =90-9x

According to question:

90-9x=3(9x+9)-9

99-9x=27x+27

11-x=3x+3 [by dividing by 9 both sides]

4x=8

x=2

9-x=7

Therefore original no.:- 10x+(9-x)=9x+9=18+9=27

Answer 2

ANSWER:

Original no. = 27

STEP BY STEP EXPLANATION:

Let,

Tens digit = x

Ones digit = y

So, no. obtained = 10x + y

By reversing the digits,

No. obtained = 10y + x

ATQ.

x + y = 9

y = 9 - x ------ (1)

And

10y + x = 3(10x + y) -9

10y + x = 30x + 3y - 9

10y - 3y = 30x - x - 9

7y = 29x - 9 ------ (2)

Using 1 in 2

7(9 - x) = 29x - 9

63 - 7x = 29x - 9

63 + 9 = 29x + 7x

72 = 36x

x = 72/36

Therefore,

x = 2

Using x = 2 in (1)

y = 9 - 2

y = 7

Thus,

No. Obtained = 10x + y

= 10(2) + 7

= 20 + 7

= 27

Hope it helps!!

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