Question

1. A number consists of two digits whose sum is 9. If 9 is added to the number its digits are inter changed. Find the number.

Answer 1

Answer:

45

Step-by-step explanation:

45 is figure whose digit sum is 4+5=9

and if 9 is added to 45 then it becomes 54 .The digits of 45 are interchanged

Answer 2

Answer:

the digit at the unit blace be x

the digit at the tens place be=9-x

so the required number will be=10(9-x)+x

=90-10x+x

=90-9x

number obtained by interchanging the digits

=10×+9-x

=9x-9

Now,ATQ

90-9x+9=9x-9

99-9x=9x-9

9x+9x=99+9

18x=108

x=6

so the required number is=90-9×6

=90-54

=36