Two 100-w light bulbs used a total of 400wh of energy. For how many hours did the light bulbs use power?

I'm assuming that you meant to write 'two 100-w per hour light bulbs used a total of 400w. how many hours did the bulbs run'so each used 100w per hour and there are 2 light bulbs so in 1 hour 200w is used200wh times x hour=200wx=400wdivide both sides by 200wx=2they ran for 2 hours