If my grade is 96.09% and i fail a 35/35 point test what will that bring my grade down to?
if i got like a 0/35 or something like that, what would it do to my grade?

It depends on the total amount of points in the class right now.

If you have, say, 9609/10000 points, Your grade would go to a 95.75%

If you have 96.09/100, your grade would go to a 71.18%.

To find this just divide the amount of points you have + the amount of points you score on the test divided by the total amount of points now + 35