Monday Mutant 24: Straight and Arrow (indirect)

In this Straight and Arrow puzzle, a number followed by a question mark represents how many black cells are in at least one of the four orthogonal directions (that is, the question mark can be replaced by an up arrow, a down arrow, a left arrow, or a right arrow, and be a normal Straight and Arrow clue). A number followed by an x means that none of the four orthogonal directions contain that many black cells. A number followed by a plus sign represents the total number of black cells in all four orthogonal directions. The rules are otherwise unchanged.
I plagiarized -- I mean stole -- I mean borrowed this mutant idea from MellowMelon.
ERRATUM: Sheesh, at this rate, my blog will have more errata than MellowMelon's blog and The Griddle combined by the end of the year! Due to my brain not working 100% properly, this puzzle had multiple solutions. . . until now.