The sum of the digits of …
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Sia ? 4 years, 6 months ago
Let,
The units digit = x
The tens digit = 7 - x
Orignal Number :
⇒ 10 (7 - x) + x
⇒ 70 - 10x + x
⇒ 70 - 9x
Digit of the number reversing :
⇒ 10x + (7 - x)
⇒ 10x - x + 7
⇒ 9x + 7
According to the question:
The number with reversed digits increases
The original number by 9 :
So,
⇒ (70 - 9x) + 9 = (9x + 7)
⇒ 70 + 9 - 9x = 9x + 7
⇒ 79 - 9x = 9x + 7
⇒ 79 - 7 = 9x + 9x
⇒ 72 = 18x
⇒ 18x = 72
⇒ x = 72 / 18
⇒ x = 4
The unit digit = 4
The tens digit = 7 - x
⇒ 7 - 4
⇒ 3
The tens digit = 3
Therefore,
The number is 34
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