To solve the problem, work from the left. Figure out which voltages are a constant on the inputs of each opamp and then figure out what output voltage on that opamp will generate the same voltage on the other input (Kirchoff or node analysis for complex ones, looks like Kirchoff is enough for this problem).
It looks like v1 = 3v (this is a buffer configuration). That means the top input for the opamp generatng v3 is also 3v. Figure out what output voltage at v3 generates 3v on the other input terminal for this opamp.
For v2, the bottom pin is at ground potential (0V). Figure out what output voltage will generate 0V at the other input. To do this, assume the current through the 5K and 20K resistors is the same and solve for the voltage across the 20K resistor. (or solve it as a voltage divider with an output of 0V). In this case v2 is -8V.
Continue with this strategy until you have all the opamps solved.
