I am a 2 digit number the sum of my digits is 12. the ones digit is twice the tens digit? who am i?

84

Step-by-step explanation:

let a be the 1's digit and b the 10's digit, then

a = 2b ← twice the 10's digit, thus

sum = 2b + b = 12, that is

3b = 12 (divide both sides by 3)

b = 4

and a = 2b = 2 * 4 = 8

The 2 digit number is 84