Two 220 volt, 100 watt bulbs are connected first in series and then in parallel. Each time the combination is connected to a 220 volt a.c. supply line. The power drawn by the combination in each case respectively will be :

The rated voltage equals the supply voltage, so we can use:
Series connection: $\dfrac{1}{P} = \dfrac{1}{P_1} + \dfrac{1}{P_2}$
Parallel connection: $P = P_1 + P_2$
Series: $\dfrac{1}{P} = \dfrac{1}{100} + \dfrac{1}{100} = \dfrac{1}{50} \Rightarrow P = 50$ W
Parallel: $P = 100 + 100 = 200$ W
Check: each bulb has $R = \dfrac{220^2}{100} = 484\ \Omega$; in series $\dfrac{220^2}{968} = 50$ W, and in parallel $\dfrac{220^2}{242} = 200$ W.
So the power drawn is 50 watt and 200 watt respectively.