Question

the sum of the digits of a 2 digits number is 12 if the digits are reversed the new number decrease by 36

Answer 1

let the two digits of two digit no. be x and y.
therefore, x+y=12....(1)
and
(10x+y)-(10y+x)=18
10x+y-10y-x=18
9x-9y=36....(2)
from(1),
y=12-x
substituting y=12-x in (2),
9x-9(12-x)=36
9x-108+9x=36
18x=36+108
18x=144
x=144÷18
x=8
substituting x=8 in (1)
x+y=12
8+y=12
y=12-8
y=4