일반물리학 2 — Circuits: Problem 65

65 A total resistance of 5.00 $\Omega$ is to be produced by connecting an unknown resistance to a 15.0 $\Omega$ resistance. (a) What must be the value of the unknown resistance, and (b) should it be connected in series or in parallel? (c) What is the total resistance if the unknown resistance is connected the other way?