I don't know how to resolve this problem.
A complete circuit consists of a 18,0 V battery (internal resistance r) and a resistor R. The terminal voltage of the circuit is 15,8 V and the current is 4,00 A. What is:
a) the internal resistor r of the battery.
b) the resistance R of the circuit resistor.
I am not sure how to resolve it. I know the Ohm's Law, but not sure how to apply it here.
Sorry for the basic question (just starting with Physics again after very long time).