What expression can be use to write the distributed property of 3x+15=?

The answer would be 3 (x+5).

If you take the GCF (Greatest Common Factor) out of 3 and 15, the greatest common factor is 3. The factors of 3 is 3 and 1 while the factors of 15 is 1, 3, 5, and 15. The highest one that matches up is 3, so you would divide the equation by 3 and then put it on the other side.

3x+15

*divided by 3*

3 (x+5)