Question

A number has a digit whose
whose sum
is 7.If 27 is added to the
number
Its digit is to be inter
changed. Find the number​

Answer 1

Solution:-

Let the ten and unit digit of the required number be x and y respectively

x + y = 7 ..........(i) (given)

Required Number = ( 10x + y )

Number obtained on interchanged its digit = 10y + x

10x + y + 27 = 10y + x

10x + y - 10y - x = - 27

9x - 9y = - 27

9( x - y ) = - 27

x - y = - 3 ....(ii)

On adding (i) and (ii) , we get

x + y + x - y = 7 + (-3)

2x = 4

x = 2

Put the value of x = 2 in (i)

x + y = 7

2 + y = 7

y = 5

Answer:- x = 2 and y = 5