Calculate value of output voltage?
I think your answer is correct. The only assumption we need to start with is that no current flows into either op amp input. That gives a +0.8V difference going from Vo to V- (0.1mA * 8 kΩ).  The difference is fixed by the current source, so when Vo changes, V- changes by the same amount. When Vo = -2.8V, V- = -2.8V + 0.8V = -2V = V+, and the output is stable.