Answer:
12
Step-by-step explanation:
Factors of 12 = 1, 2, 3, 4, 6, 12
Factors of 24 = 1, 2, 3, 4, 6, 8, 12, 24.
Common factors of 12 and 24 = 2, 3, 4, 6, 12
Highest Common Factor = 12