Let the roots be p and q
If the sum of the root is 16/3, it means that p + q = 16/3
If the product of the roots is - 4, it means that pq = - 4
From pq = 4, q = 4/p
Substituting q = 4/p into p + q = 16/3, it becomes
p + 4/p = 16/3
Multiplying both sides of the equation by 3p, it becomes
p * 3p + 4/p * 3p = 16/3 * 3p
3p^2 + 12 = 16p
3p^2 - 16p + 12 = 0
The equation is
3p^2 - 16p + 12 = 0