If they are in series, the total resistance is 150 ohms so the current is 120/150 amps. If they are in parallel, the current is 120/100 plus 120/50 amps.
Resistances in series circuits are additive. The equation that your are looking for is I = E/R. Amps = Voltage/Resistance.
The equation you are looking for is I = W/E. Amps = Watts/Volts.
0v The relay is designed to act as a switch when voltage is applied across the coil. The contacts open or close but only pass through whatever is connected to those terminals. <<>> When a relay coil is energized the relay's contact change status. The closed set of contacts will open. The 120 volt circuit that is connected will turn off. As to the voltage at the contact terminals, it depends on where you are taking the voltage reading from and to. On the source side of the terminal there will be a reading of 120 volts to neutral or ground. On the other side of the contact terminal there will be zero volts to the neutral or ground. This is because that wire is in series with the load to neutral. A meter reading across the relay terminals will read 120 volts.