Aclothes dryer in a home has a power of 4,500 watts and runs on a special 220-volt household circuit,
1.what is the resistance of the dryer?
2.what is the current through the dryer?
3.how many kilowatt-hours of electricity are used by the dryer if it used for 4 hours in one week?

1).  Power = (voltage)² / (Resistance)

     4,500 = (220)² / Resistance

Multiply each side by (resistance) :  4,500 x resistance = (220)²

Divide each side by  4,500 :            Resistance  =  (220)² / 4,500 = 10.76 ohms

2).  Power = (voltage) x (Current)

Divide each side by (voltage):  Power / voltage = Current

                                            4,500 / 220  =  20.45 Amperes

3).  4,500 watts = 4.5 kilowatts

     (4.5 kilowatts) x (4 hours)  =  18 kilowatt-hours