[trainee]

I must've scoured a dozen articles but I feel like I keep going in a circle and I'm about to lose it.
The equation I was given was this:
U = Q - W
Does this imply
W = -PΔV?
And if I get a negative number (-x) it will end up something like
Q - (- x) = Q + x?
Or is this negative part of the -W so
U = Q - x?

I know this should be really easy but I'm about to go crazy. The different sign conventions (I was told - was more common in chemistry but a lot of chem resources seem to use + like in physics?) are driving me crazy.