how can snakes breath when they have a goat half way down there throat?

Answer 1

Their nostrils and airway are separate from their gullet.

Answer 2

The pallet at the roof of their mouths allows air to still pass into the trachea while the oesophagus is clogged with prey. This is also common with mammals like us for instance, we can still breath while eating, it all works in the same fashion.

Hope this helps!

Answer 3

do you mean how do snakes lungs expand in that situation?
if so then they probably have extra space in their rib cage for their lungs to expand.