The voltage v in a simple electrical circuit

The voltage V in a simple electrical circuit is slowly decreasing as the battery wears out. The resistance R is slowly increasing as the resistor heats up.
Use Ohm’s Law, V=IR, to find how the current I is changing at the moment when R=400ohm. I=0.08A, dV/dt=-0.01V/s, and dR/dt=0.03ohm/s