1/2-j+2=4/2-j
First of all, you can see that your j's will cancel each other out. Therefore, there are two possibilities outcomes. You will either have infinitely many solutions or no solutions, depending on the equality of the constants that are left.
1/2 + 2 = 4/2
As you can see, 1/2 + 2 when simplified is 2.5 or 5/2 which cannot possibly equal 4/2 or 2. Therefore, this equation has no solutions. Had these two values been equal, then you equation would yield infinitely many solutions.