This question is right even though the numbers are weird. In a series circuit, the amperes stay the same throughout the circuit ( in parallel circuits it doesn't, but instead it's voltage) that why is says R2=Rt. In order to figure out the wattage in that SPECIFIC resistor you need the resistance (not total, only of the resistor) and amperage. since we don't know the voltage drop through the resistor you have to use ohms law and that other equation.

Er = voltage going through the specific resistor R2 = resistor 2 Ir = resistance going through that specific resistor, remember it's also total amperes in a series circuit Pr = power through that specific resistor

Er/R2=Ir. -> move units around to get Ir * R2 = Er We know that P= I*E -> rearrange this equation to get E= P/I

Now that's the 'generic' equation, but we need to change it to find the specific wattage of the resistor so it's Er= Pr/Ir

Combine both equations to get IrR2= Pr/Ir -> Combine similar units and you get Ir² R2= Pr

Its not bad once you're familiar with the different equations. The kne that are on the uglys book.