It depends how formal a solution you need:
For a back of the envelope calculation, as one of your sources is fixed -5V, you can simply take all voltages with respect to that point, (i.e. treat the other source as pulsing from +8V to +5V), and use the usual potential divider formulae to solve it for the two voltage levels of the pulse. If you need the result referred to your original 0V point (rather than across R2), you'd then need to subtract 5V.
More formally, you could use
Superposition and
Thévenin's theoremHowever if you are a university student, unless you have explicitly been told otherwise, the instructor is probably looking for a solution based on Nodal or Mesh analysis.
The numerical results for all methods applied to this circuit *are* equal, so if you solve it by more than one method and yours are different you've made a mistake.