I am a multiple of 7. my ones digit is half of the tens digit. If you double it , you get a number between 40 and 50. When you add it to an odd number , you get an even number.

Answer 1

u want the answer

Answer 2

odd+odd = even, so the number after doubling must be odd.
Since doubling produced a number in the 40's, the original number must be in the 20's.
Looks like 21 to me

Answer 3

18