You have the following expression:
(3x + 1)(2x - 1) = 0
by using the zero product property, you have that the either the first factor is zero or the second one is zero.
Hence, you have:
3x + 1 = 0
3x = -1
x = -1/3
2x - 1 = 0
2x = 1
x = 1/2
The solutions are -1/3 and 1/2