Question

Sum of the digit of two degit is 9.
also nine times this no.is twice the
number obtained by reversing the
order, find the No.?​

Answer 1

Answer:

Let the two digit number be 10x + y.

Given that sum of the digits = 9

⇒ x + y = 9 ------(Equation 1)

10y + x is the reverse of our require two digit number.

Given 9 times of our number is equal to twice the reverse of our number.

⇒ 9(10x + y) = 2(10y + x)

⇒ 90x + 9y = 20y + 2x

⇒ 88x - 11y = 0

⇒ 8x - y = 0 -------(Equation 2)

Adding equation 1 and 2

We get,

9x = 9

x = 1

x + y = 9

⇒ y = 8

Our required two digit number is 10x + y = 18.