Answer:
3n(5m+z)
Explanation:
First work on the whole numbers. 15 and 3 have a GCF of 3 so you factor that out.
It becomes 3(5mn +nz)
The variable "n" is still a common factor between the two numbers so you can factor that out as well
The equation finally becomes 3n(5m+z) which is the most you can factor.