The circuit shown in Figure 1 is a 4-input inverting adder circuit, which is similar to the example that we covered in lecture. Answer the following questions: a) Using the "Golden Rules" and KCL, derive an equation for Vout for this circuit. b) Assuming R1 = 800 Ohms, R2 = 400 Ohms, R3 = 200 Ohms, R4 = 100 Ohms and Rf = 800 Ohms, what is Vout, when V1 = 5V, V2 = 4V, V3 = 3V, and V4 = 2V