Question

In a two digit number , digit in units place is twice the digit in tens place. if 27 is added to it , digits are reversed . Find the Number.

Answer 1

let u=units digit
let t=tens digit
u=2t
..
digits reversed:
10u+t=10t+u+27
20t+t=10t+2t+27
9t=27
t=3
u=2t=6
number:36

Answer 2

Let the no is 10x + y

y = 2x eq1

10x + y + 27 = 10y + x

9x - 9y = -27

Take 9 common

x - y = -3 eq2

put y = 2x in eq2

x - 2x = -3

x = 3

put x in eq1

y = 2x

y = 2 × 3 = 6

10x + y = 10×3 + 6 = 36

So Number is 36


Thanks