Question

The sum of a two digit number and the number obtained by reversing the order of its digits
is 121. If units and ten’s digit of the number are x and y respectively then write the linear
equation representing the above statement.

Answer 1

Total original number is 10y + x
The new number is obtained after reversing the order of digits is  (10x + y)
According to problem 

( 10y + x ) + ( 10x + y ) = 121

⇒  11x  +  11y = 121

⇒  11 (x + y ) = 121

⇒   x + y = 11

Thus is the required linear equation for the given information