Answer:
72
Explanation:
To be divisible by 4, the number must be even, so we can eliminate 63 and 73 (There are other restrictions for 4, we just want to eliminate answers that cannot be true)
We have only 2 answers left
64 and 72
To be divisible by 3, the sum of the digits must be divisible by 3
6+4 = 10 which is not divisible by 3
7+2 = 9 9/3 =3