Question

the sum of a two digit number and the number obtained by reversing is 121. find the number if its unit place is 5​

Answer 1

$\huge\color{red}{Solution❤}$

Given units digit is x and tens digit is y

Hence the two digit number = 10y + x

Number obtained by reversing the digits = 10x + y

Given that sum of a two digit number and the number obtained by reversing the order of its digits is 121.

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

⇒10y+x+10x+y=121

⇒11x+11y=121

⇒x+y=11

Thus the required linear equation is x + y = 11.

x given (unit place) = 5

putting 5 in equation:- 5 + y = 11

Hence y = 6

x = 5 y = 6

Required number is = 56

Answer 2

Given units digit is x and tens digit is y

Hence the two digit number = 10y + x

Number obtained by reversing the digits = 10x + y

Given that sum of a two digit number and the number obtained by reversing the order of its digits is 121.

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

⇒10y+x+10x+y=121

⇒11x+11y=121

⇒x+y=11

Thus the required linear equation is x + y = 11.

x given (unit place) = 5

putting 5 in equation:- 5 + y = 11

Hence y = 6

x = 5 y = 6

Required number is = 56