Answer:
(3x + 1) (5x - 3)
Explanation:
first multiply 15 by -3 to get -45, then find 2 numbers that multiply to get -45 that also add/subtract to get +4. you will get 5 and -9. Replace the 4 with those numbers and distribute. Find the common factors once you have 2 seperate brackets.
(see photo)