The hammer throw has the same grip as what throw?

Could someone me find the answer to this problem.

Aresistor with an unknown resistance is connected in parallel to a 9 ω resistor. when both resistors are connected in parallel to an emf source of 21 v, the current through the unknown resistor is measured with an ammeter to be 4 a. what is the resistance of the unknown resistor? answer in units of ω.

Acamcorder has a power rating of 20 watts. if the output voltage from its battery is 9 volts, what current does it use?