Question

The sum of the two digit no. is 12. The no. Obtained by interchanging the two digit exceed the given no. by 18.find the no.

Answer 1

let the digitz b x and y

x+y=12

the two digit no..10x+y

interchangd no... 10y+x

10x+y+18=10y+x

9x-9y=18

x-y=2....(i)

x+y=12

using eliminatn methos u get the value of x and y as 5 n 7 ...thus the number is 57 or 75

Answer 2

let no be 10y+x according to question x+y=12......(i) & (10x+y)-(10y+x)=28 so x-y=2...(ii)
solving (i) &(ii) we get x=7 & y=5 so no is 75.