Answer:
15
Explanation:
LCM is the least common multiple, that is, is the least number that is a multiple of both numbers.
To find it, first, let's write the multiples of 3:
Multiples of 3: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, ...
Now, let's write the multiples of 15:
Multiples of 15: 15, 30, 45, ...
If you compare the multiples of 3 and 5, we can see that they have some common multiples, as 15 and 30.
From this common multiples, 15 is the smallest number. So, 15 is the LCM of 3 and 15.
Answer: 15.