I need help finding an answer out.. this is self study and I have the some formulas but cant see the trees through the forest. here it goes:

Self Test question #8 from Electronics Self Teaching Guide by Earl Boysen Pg 36.

Parallel circuit:

Vs=12v

I=300mA

R1=50ohms

I need to find the following:

ohms for R2 and watts for P1

I found watts for P1 =2.88 by the P=V2/r

But I can not find R2.(which the answer has 200ohms). I keep on getting 9.18w for P2 and then my mind goes dumb.

Please help with more then two sentence blurb.. Please explain how to find the R2 amount.