Take a look at
this website. It explains RV electric systems
Watts
Watts are the standard unit of measurement of electrical power. One watt is one ampere of current flowing at one volt
Volts
Voltage is the potential energy in a circuit before amperage and resistance come into play. The term volts refer to the line electricity runs through, or how fast the electric runs through that line.
Amps
Amperage is what costs you the money on your electric bill. Amperage is the actual current being pulled from the line. Amps is a measure of the wattage divided by the voltage, A=W/V.
Watts = Amps x Volts
Volt = Watts / Amps
Amps = Watts / Volts