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A number consists of two digits. The sum of the digits is 9. If 45 is subtracted from the number, its digits are interchanged. What is the number?

A number consists of two digits. The sum of the digits is 9. If 45 is subtracted from the number, its digits are interchanged. What is the number? Correct Answer 72

Let the two-digit number is AB

The sum of digits = A + B = 9

If 45 is subtracted from the number, its digits are interchanged.

⇒ 10 A + B – 45 = 10 B + A

⇒ A – B = 5

⇒ A = 7, B = 2

The required number = 72.

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