Resistance = (voltage) / (current)
Resistance = (120 V) / (0.5 A)
Resistance = 240 ohms
Know what ? There might be too much information given in this question. I want to check, because it's possible that it might not even all fit together.
To calculate my answer, I only used the voltage and the current. I didn't use the "60 watts", and I'm curious to know whether it even fits with the given voltage and current.
Power = (voltage) times (current).
Power = (120 V) times (0.5 A)
Power = 60 watts
Well gadzooks and sure enough ! The three numbers given in the question all go together nicely.
And not only THAT !
The answer could have been calculated by using ANY TWO of them.