The current in a hair dryer measures 19 amps. the resistance of the hair dryer is 14 ohms. what is the voltage?

Voltage  =  (current) x (resistance)

             =  (19 A)  x  (14 ohms)  =  266 volts .

Note:  Be careful using that thing ! 

It's dissipating

       I² R  =  (19 A)² x (14 ohms)  =  5,054 watts ! ! !

That's an awful lot of power for a blow-dryer ! 

The dryer is certainly not using very much of that power to run the fan. 
Most of it is being used to heat air.  5 kilowatts is more power than most
toasters or microwave ovens use, so please be careful with how much of
your hair or skin you expose to that hot-air blast.  You could probably cook
a meatloaf with it.