My mo when attacking a question of this nature on a test was to write down as many equations as I knew in the subject matter of the test, start plugging numbers into these formulas, circling various parts of my problems at random, erasing them to smudge them just enough to be somewhat difficult to read, and listing my assumptions and constraints when working the problem. I don't think I ever got a single problem entirely right in my illustrious academic career on the North Ave. but through liberal application of both partial credit and the curve, I got out.