Answer:
4x-15 <---
Step-by-step explanation)
1) Distribute the X to both the x and the -3
2) You'll end up with, 5x-15-x=...
3) And, now look at the like terms. The like terms in this case are 5x and the -x.
4) 5x-x =4x
5) And, now put them together, and you'll get 4x-15!
HOPE IT HELPS! <3