Answer:
27
Explanation:
Division rule for 3: Sum of the digit is divisible by 3.
Division rule for 9: Sum of the digit is divisible by 9.
Lets define x as the missing digit.
7 + 6 + 8 + 4 + x = number divisible by both 3 and 9
7 + 6 + 8 + 4 = 25
25 + x = number divisible by both 3 and 9
Since a single digit cannot be 10 or greater, we have 5 numbers that are possible.
25, 26, 27, 28, 29
Which one is divisible by 3 and 9?
27