Answer:
The readings would have the same value, but it would change the sign. It would have a minus sign (-) .
Explanation:
Assuming the battery mentioned is part of some basic circuit (just a power source and some resistive elements or switches), and the ammeter and voltmeter are measuring some variable inside this circuit, then the readings would change his sign, but the absolute value will remain.
This happens because the ammeter is measuring the electron flow, and since there is a change in the reference terminal, it would “see” a change in the direction of the electron flow.
Same for the voltmeter, there is a primary reference for the electric potential (capacity to go, from one side to another from the electrons) if the reference change, the potential would be inverted.
