[plshelpthisperson]

I understand how to do most oxidation states but there are a few questions I have to do where the format of the molecule is written differently and I can't figure it out.
For example: Cl3Al-PH3
I don't know why there's a line in between Al and P. There's another where there's a = in between two of the atoms. What does that mean? (Bond?  But why is it written like that?)

Also, when I tried to solve it:
The two I know are Cl and H:
Cl:-1 (3)
H: (+1) (3)
But then the net is 0.   How am I supposed to know what P and Al are then?

Thanks for your help

[Vidya]

This line indicates that it is a dative bond where N is giving its lone pair for making a bond with Al .
ON number of Al is still +3 and P is -3