

Let 10s digit of the number is x and unit digit of the number is y
So, the number = 10x + y
When the number is reversed = 10y + x
Given, nine times a two-digit number is the same as twice the number obtained by interchanging the digits of the number
=> 9(10x + y) = 2(10y + x)
=> 90x + 9y = 20y + 2x
=> 90x - 2x = 20y - 9y
=> 88x = 11y
=> y = 88x/11
=> y = 8x .................1
Given, one digit of the number exceeds the other number by 7
=> y = x + 7
=> 8x = x + 7
=> 8x - x = 7
=> 7x = 7
=> x = 7/7
=> x = 1
Now, y = x + 7 = 1 + 7 = 8
So, the number = 10 * 1 + 8 = 10 + 8 = 18
