Answer:
k = - 4
Explanation:
given a quadratic equation in standard form
ax² + bx + c = 0 ( a ≠ 0 ) , then the product of the roots is

3x² + 5x + 3k = 0 ← is in standard form
with a = 3 and c = 3k , then
= - 4 , that is
= - 4 ( multiply both sides by 3 to clear the fraction )
3k = - 12 ( divide both sides by 3 )
k = - 4