Question

1.   Nine times a two-digit number is the same as twice the
number obtained by interchanging the digits of the number. If one digit of the
number exceeds the other number by 7, find the number. 

Answer 1

unit digit is >tenth digit since after multiply with 9 we get   twice of  reverse number .....

so consider left is (x+7) and right digit is x.....
now 9*(10*x+(x+7))=2(((x+7)*10) +x)
⇒ 99 x+63= 22x +140
⇒77x=77
⇒x=1......
so another no is 8...so number is 18...