How do I finish factoring this trinomial

5v^2 - 20v + 15
5(v^2 - 4v + 3)
a=1 b=-4 c=3
ac=3
... I can't think of anything that multiplies to ac and adds to b.

-1 and -3
5(v -1) (v - 3)

v² - 2v = - 3 + (- 2)²
v² - 2v = - 3 + 4
(v - 2)² = 1
v - 2 = ± 1

= v - 2 + 1, v = - 1
= v - 2 - 1, v = - 3

Answer: 5(v - 1)(v - 3)

(v - 3)(v - 1) = v^2 - 4v + 3