This document contains 3 problems involving BJT transistor circuits: 1) A 2N3904 npn transistor circuit is given and the collector current is calculated as 7.57mA. 2) A BUV21G transistor circuit is given and the collector-emitter voltage is calculated as 27.67V. 3) A complex transistor circuit is shown and broken down using Thévenin's theorem. The operating point is calculated with a base current of 17uA and a collector current of 2.87mA, giving a collector-emitter voltage of 11.99V.