Question

a number consist of of two digits whose sum is 8. if 18 is added to the number its digit are reversed. find the number.

Answer 1

let digit at tens place be x and units place be y
hence no is 10x+y
now x+y=8........1
and
10x+y+18=10y+x
9y-9x=18
y-x=2..........2
by 1 and 2
2y=10
y=5
x=3
no is 35

Answer 2

X+y = 8
10x + y +18 = 10y + X
10x-x+y-10y = 18
9x-9y = 18
9(x-y) = 18
x-y = 2

X = y-8
8-y-y= 2
-2y = -6
2y=6
y= 3
X+y = 8
x= 8-3
= 5
therefore the numbers are 35 and 53
35+18= 53
hence proved