Question

sum of the digits of a 2 digit number is 9.if 45 is subtracted from the number, the digits interchange their places. find the numbers

Answer 1

Suppose the digit at ten's place  = x

and at unit's place = y

number becomes    10x + y

according to statement

x + y = 9

and

10x + y  -  45  = 10y + x

9x - 9y = 45

or

x - y = 5    ---  (2)

Solving (1) and (2)

x + y  = 9

x - y = 5

adding

2x = 14

x = 7

x +y = 9

y = 9 - x

y= 9 - 7

y = 2

So Number is

10*7 + 2 =   72

Two digit number is 72

Answer 2

plz tell me my answer is right or wrong ....