Answer:

Step-by-step explanation:
We analyze between which prime numbers we can divide the number 30. The smallest prime number by which we divide is 2. Then:

We now look for the smallest prime number that divides the 15. Since 15 is not a multiple of 2, we make the division with the number 3 that is divisor of 15.

We now look for a number that divides to 5, but since 5 is a prime number, the only divisor other than 1 is 5. Then:

This ends the decomposition of 30 and we find 3 prime factors:
2,3 and 5.