In order to solve this problem you need to set up an equation.
12 = x + (x + 4)
x will represent the number of women, and (x+4) will represent the number of men, because there are 4 more men than women.
12 = x + x + 4
12 = 2x + 4
8 = 2x
x = 4
This is the answer to how many women there are, but your question is asking for the number of MEN, so we have to go one more step farther. Like stated before, the expression for the number of men is shown like so: (x +4). Now we just need to plug in the number for x.
(x+4)
4+4
8
There were 8 men on the jury.