Question

3. A two digit number is seven times
the sum of its digits. The number
formed by reversing the digits is 18
less than the given number. Find the
given number.​

Answer 1

Let the two-digit number be 10x+y

given,the number is 7 times the sum of its digits

⇒10x+y=7(x+y)

10x+y=7x+7y

3x=6y

x=2y

the number formed by reversing the digits is 18 less than original number

⇒10x+y-(10y+x)=18

   10x+y-10y-x=18

   9x-9y=18

  9(x-y)=18

  (x-y)=18/9=2

⇒x-y=2

x=2y

⇒2y-y=2

y=2

x=4

∴the number is 42