268. In the circuit contained in Fig. 8F12, there are 5 volts present at points B and C, and there are zero volts present at points A and D. What is the voltage at point E?

The voltage at point E is -1.5 V. In an inverting summing amplifier, the output is the negative, scaled sum of the input voltages. Since points A and D are at 0 V, they do not contribute to the output. The two inputs at points B and C, both at 5 V, contribute equally, resulting in a negative output of -1.5 V based on the circuit's gain.