Replying to Proving teacher wrong (test question)

Hey guys, need help to settle a dispute between me and my auto teacher.

on our test, we had the question "________ law states that: when __________ is applied to a ________ fluid, pressure is _______________ and undiminished througout the system."

for the last blank, i wrote in the word 'constant'. my teacher says that the proper word is equal, im saying that using constant instead of equal means the same thing. if there is 50 pounds in one area, that pressure will equal the pressure anywhere else in the system. Im saying that the pressure in one area will be CONSTANT  throughout the whole system.
he let the word "even" count for a mark as well.
so ns, what do you think?
in this question, is constant a valid answer?