Question

A two digit number is 9 times the sum of its digit.If its unit and tens digits be x and y respectively,write this information in the form of a linear equation in two variables.

Answer 1

let any number = 10y + x

here x is unit digit and y is tens digits
a/c to question,

10y + x = 9 (x + y )

y = 8x

Answer 2

Let the unit digit be x
            tens digit be y
The two digit number =10x+y

According to the given statement , the information can be written in the form of linear equation 
          ie, 10x+y= 9(x+y)
               10x+y= 9x+9y
               10x-9x+y-9y=0
              
                x-8y =0