Mechanics Help, unsure on how to do this

Which object is most likely represented by a dot?

Acertain radio station broadcasts radio waves that have a wavelength of 298cm what is its broadcast frequency?

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.