Power= (voltage)*(volatage)/Resistance
From above relationship , Power is inversely proportional to Resistance.
So,More Power less resistance,Less Power high resistance.
25 W bulb has higher resistance .
If P1=50W and P2=25W
Then P1=V1*V1/R1
         on dividing the above two equations we get,
         So, Bulb 1 ( 50W) has higher resistence by a factor of 2 or 2 times than              bulb with 25W.

         P.S. I think if you use pen and paper to solve the above question , It will            help you. Good luck 

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