Question

the digit of a 2 digit no. differ by 5. if the digit are interchanged the resulted no. to the orginal no. we get 99 find the orginal no.​

Answer 1

Answer:

Let the unit digit be 'x'. And the digit at the tens place = (x + 5).

∴ Original number = 10(x+5) + x

After interchanging digit, the new number = 10x + (x + 5)

According to the question ;

[Original no] + [new no] = 99

⇒ 10(x+5) + x + 10x + (x + 5) = 99

⇒ 10x + 50 + x + 10x + x + 5 = 99

⇒ 22x + 55 = 99

⇒ 22x = 99 - 55

⇒ 22x = 44

⇒ x = 44/22

⇒ x = 2

Unit digit = x = 2

Tens digit = x + 5 = 7

∴ Required number = 72