Two batteries have unequal emf's of 2 V & 3 V, respectively, & equal internal resistances of 0.35 Ω. One end of a 4 Ω resistor is connected to the positive terminals of the batteries & the other end is connected to the negative terminals. Make a circuit diagram & use Kirchhoff's rules to find the voltage across the 4 Ω resistor.
(Note: This circuit is like part of the Hodgkin-Huxley model for how action potentials in neurons are initiated. The emf's are like the electrochemical gradients driving the flow of ions; the resistor replaces the current source representing ion pumps & exchangers; & there is no capacitor representing the lipid bilayer membrane.)