Depends on the inputs available on the projector, the outputs available on the PC laptop, and the outputs available on the document camera. Also, if you want to display both at the same time, the projector needs P-i-P, i.e. Picture in Picture.
If all you've got are VGA outputs (the laptop and the document camera) and inputs (on the projector) - if you're lucky, the projector can have two VGA inputs at the same time. If you're unlucky, then you need a codec or selector to switch between sources without replugging stuff.
But again; this depends (obviously) on the hardware you've got, and you didn't even begin to give any detail about that.
Comments
Depends on the inputs available on the projector, the outputs available on the PC laptop, and the outputs available on the document camera. Also, if you want to display both at the same time, the projector needs P-i-P, i.e. Picture in Picture.
If all you've got are VGA outputs (the laptop and the document camera) and inputs (on the projector) - if you're lucky, the projector can have two VGA inputs at the same time. If you're unlucky, then you need a codec or selector to switch between sources without replugging stuff.
But again; this depends (obviously) on the hardware you've got, and you didn't even begin to give any detail about that.