Help with a science formula?

Question

How long will a 75 W bulbl glow for on 1 kJ of energy?

Please tell me how you do it?

Answer 1

This is not my area but I would think it is something like this:

energy input = electricity used (in watt-hours) =

(power rating, in watts) x (time of operation, in hours)

1kJ = 75W x t

1kJ/75W = t

1,000J/75W = t

t = 13.333

13hrs 20 min

Answer 2

1kJ = 1000J

a joule is a watt second

so 1000 w-sec / 75 w = 13.3 seconds