if you use the right hand grip rule to work out the magnetic fields surrounding them it's easy to figure out
kinda difficult to type up actually now that i'm trying lol but if you do the grip rule around wires carrying current in same direction, between the two wires the magnetic field from one comes out of page and from other into page so they attract
if they are in opposite directions the magnetic field between the two wires either both comes out, or both into the page and they repel
i hope that makes sense it's really hard to explain without diagrams