When a 220 V, 100 W light bulb is connected to a 220 V power supply through a section of wire, its actual power is 81 W, then how much power is lost on the wire?

When a 220 V, 100 W light bulb is connected to a 220 V power supply through a section of wire, its actual power is 81 W, then how much power is lost on the wire?

Answer: 9W
Analysis:
Resistance of lamp: R lamp = u ^ 2 / P = 220 × 220 / 100 = 484 Ω
Actual power: P = u ^ 2 / R lamp
That is: 81 = u real ^ 2 / 484
The result is: u = 198v
Therefore, the conductor voltage is u '= 220-198 = 22V
The ratio of voltage is equal to the ratio of actual power
That is: 81: P loss = 198:22
P loss = 9W
I don't know what to ask

Two 100W bulbs are connected in series to the power supply of 220V. The power of each bulb is, and the calculation formula is?

25w