Question

a number consists of two digits whose sum is 6 .if 18 is added to the number, it's digits are reversed. find the number

Answer 1

let the digit in the units place be x.
then the digit at the tens place=6-x
original number= 10*(6-x)+x = 60-9x
on reversing the digits-
new number= 10x + 6-x
=9x+6
original no. + 18= new number
60-9x+18= 9x +6
78-9x= 9x +6
9x+9x= 78-6
18x= 72
x = 72/18
x= 4
original no. = 24

Answer 2

one's digit=x
ten's digit =6-x

the original no. = 10(6-x)+x
the reversed no. =10x+(6-x)
difference between both no.=18

so equation formed is

10x+(6-x) - [10(6-x)+x] = 18

10x+6-x - [60-10x+x] = 18

9x+6 - [60-9x]= 18

9x+6 -60+9x =18

18x-54=18

18x = 18+54

18x =72

x = 72/18

x= 4


one's digit = 4
ten's digit = 6-4
=2

the number is 24